REPORT ON THE GEOLOGY

WOODLARK ISLAND.

Bt EVAN R. STANLEY.

c. 10048.

NOT TO BE TAKEN FROM t h e LIBRARY,

REPORT O F THE GEOLOGY OF WOODLARK ISLAFD.

B y E v a n B . S t a n l e y .

INTRODUCTION. The accounts of the discovery of Murua, now called Woodlark, appear :to be very scanty and meagre, and much difficulty was encountered in arriving at any information at all satisfactory. Louis Voez de Torres * *§ is credited with being the discoverer of the -Louisiade Archipelago in 1606. Among the first to visit the Archipelago were the French navigators, t who explored some of the islands of the group in the years 1766-1769. Later, in 1793, Bruny-D’EntrecasteauxJ passed through these waters, and the group of islands received his name accordingly, but in these cases no mention is made of Murua. The earliest available information of Murua was the establishment of a Marist mission§ in 1847. It was abandoned in 1852. They were followed by Italian missionaries || the same year, who, like their pre­ decessors, abandoned it soon afterwards. The geological pioneer of New Guinea is Mr. John McGillivary,H of H .M .S. Rattlesnake, who visited the Archipelago in the years 1846-1850. The only geological data prior to my visit to Murua is that published bÿ H . R. Maguire,** who refers to the occurrence of schists with gold- bearing quartz veins, and what information is to be obtained from the Annual Reports. Some years ago, the man-of-war Woodlark visited Murua, and since then it has borne the name of that vessel. Gold was first discovered in the vicinity of Suloga Bay, at two places almost simultaneously, some fifteen Or sixteen years ago. In June, 1895, Messrs. Ede, Lobb, and Soelberg prospected at Suloga -and Okiduse, situated on the southern coastline of Murua. Good indication of gold was obtained from each locality, and, later on, an abundance of alluvial gold was discovered. At Okiduse, a very rich patch of 500 q z s . was unearthed, being slightly water worn. In December of the same year good alluvial deposits were discovered at New Chum’s Gully, now known as Karavakum, or Boniavat. Karavakum was the first locality on the island in which a large number of men worked, there being at the time 300 or 400 men on the spot. Shortly after this important rush K ulu­ madau was discovered, and worked for alluvial. Here reefs were first discovered, and extensively worked in or about the year 1900 by the Wood­ lark Island Proprietary Company and the Ivanhoe Company. These com­ panies subsequently sold out to the Kulumadau (Woodlark Island) Gold Mining Company Limited, which company is working the greater part of the lode at Kulumadau at the present day.

* Animal Report, B.N.C. -j- “ Voyage autour du monde,” par La Bondeuce et La Flute L’Etoile, 1766-1769. j “ Voyage de Bruny D’Entrecasteaux, 1793.” § “ Histoire de la Premiere Mission Catholique au Vicariat de Melanesie, by Verguet. I| Annual Report B.N.G. 1890-1891. •if Ibid. ** “ Impressions of a Year’s Sojourn in B.N.G.,” by H. R. Maguire. 0 . 10048. 2

Soon after the Kulumadau rush, McKenzie’s Creek, situated inland about 6 miles from Kulumadau, was discovered. Several thousand ounces were obtained in a very short time , This locality undoubtedly holds the record for the greatest quantity of alluvial gold yet obtained on the island. Simultaneously with McKenzie’s Gulley, Eusai, situated about 3! miles from Kulumadau, was discovered. In the creeks about this locality much gold was obtained, and although some o f the alluvial areas have been worked several times, there is still a considerable quantity of the native metal to be extracted from them. Within recent years, several payable reefs have been discovered in the neighbourhood of Busai. Besides the above-mentioned localities, there are other places which have yielded larger quantities of alluvial. Such are Sinkurai, situated on the head waters of the Sinkurai, and Munkiai River, Reilly’s Creek, about i mile from Busai, and Wonai and the Ben, situated on the southern portion of the Okiduse Range. Much of the foregoing information was obtained from some of the oldest residents, together with the available data from, the Annual Reports. The examination of Murua extended over a period of four and a half months, during which period a geological map of the island was prepared, and the principal mining centres examined and reported upon in some detail. Owing to the impenetrable forests, swamps, continual rain, and rough country, progress was somewhat impeded. There are no means o f locomo­ tion, except faire la ronde, and, where this was impossible, a whaleboat or native canoe was resorted to. Many o f the conclusions arrived at have been based largely upon field observation. I regret to say that, as this section of the Mines Department has just been instituted, the amount o f detail required in a report o f this description will be wanting. Only a limited amount o f laboratory work has been done, thus making this report, in a sense, incomplete.

PHYSIOGRAPHY. Area and Position.— The island o f Murua, with, its adjacent islets, is situated approximately between longitudes 152, 25' E., and 153, 5' E., and latitudes 8, 55' S., and 9, 15' S. It has an area of about 370 square miles, of which there are about 50 square miles of mineral bearing country. Communication.— The only means of communication with the outside world are when the s.s. Matunga and the s.s. Mindoro arrive, the former once in six weeks, the latter once a month. These steamers connect with the other Papuan ports, and with steamers from Australia and eastern waters. It is unfortunate that there is no telegraphic^ communication, but such inconvenience can be obviated by the installation of a wireless telephone station. There are no suitable vehicular roads in Murua. The mining centres are connected by tracks suitable in part for pedestrian and horse traffic. Road construction would not be difficult, as very little grading is required, and there is stone suitable for the purpose in the localities through which the roads would pass. Tomography.— Murua has a linear extension o f 44 miles, and trends in a W.N.W. and E.S.E. direction. Its width is irregular, varying from 5 to 10 miles in the western portion, and from 10 to 20 miles in the eastern and middle portions. The principal harbors are Buyuesi, Guasopa, Suloga, Wonai, and Kwaipan Bays, in which there are anchorages for 3

deep-sea boats, the latter being the present port of entry. The island is surrounded by numerous and dangerous coral reefs, and a few smaller islands. In two or three localities portions of the main island have been detached by small canal passages, which, are either wind or water gaps, as, for example, Nasai and Monvauva, situated respectively on the southern and western portions of the island. The Mellin Group, Nubara, lone, Panamana and Ginara Islands, &c., are low-lying coral islands on the exterior portions of the reef. The mountainous country is restricted more or less to the central north­ eastern portion, where there is a range of hills trending north-east and south-west, with an altitude of about 1,000 feet. The south-west extreme reaches a height of 1,300 feet at Suloga Hill, and abruptly terminates at the north-east extreme in Kabat, which is 740 feet. Apart from the Okiduse Range, and situated to the westward, is the Kulumada.u Hill, which has a more northerly trend, and is low-lying swampy country, with numerous hillocks of coral limestone. The limestone and swampy country is met with in the western portion, o f the island, but on the northern coast­ line and eastern portion there are high cliffs and hills, with a few elevated inland swamps. Near the ranges, and overlying the coral limestone, there are numerous alluvial deposits which have been and are being worked for gold. Rivers and Creeks.— Although Woodlark is such a small island it possesses several rivers which are at all times plentifully supplied with water, owing largely to the continued and excessive rainfall. These take their sources in the Okiduse Range, and are fed by numerous streams both in the high and lowland country. The Muniai River is the largest, and flows irregularly in a westerly direction through the coral country, and meanders in the swampy mangrove country to the west of Karavakum., Use is made of this river, as it is navigable as far as the Karavakum bridge. Of the other rivers the Sinkurai, Munkiai, and Lafuai flow easterly through similar country, and are partly navigable. To the westward there is a series of creeks which drain the swampy country inland. Water Supply.—Woodlark is provided with an excellent water supply* the average rainfall being about 15 feet a year. This useful factor,, though always in demand in Australia, is at times a serious inconvenience to mine properties on Woodlark. The rapidly flowing portions of the rivers in the vicinity of the mining leases could be in some cases effectively used for power. Climate.— Though situated on the 9th latitude, Woodlark is out of the belt of cyclonic storms. There are two' seasons, one in which the south­ eastern trades prevail and the other the north-western monsoons, but there is very little difference, as far as climate is concerned, between them. The island is not an unhealthy place to live in, there being little sickness throughout the year. Being in the tropics, it is not without a few of the tropical diseases, but to one who has lived in Papua, suffering from such, diseases is known to be somewhat overrated.

GEOLOGY. Judging from the salient features of the country, the island appears to have been subjected to a series of elevations and subsidences, and latterly to an elevation o f about 500 feet. That the island was much smaller than it is at present is known by the occurrence of the later limestone deposits. Kulumadau H ill, Mount Rabat, Ormanau, the Okiduse Range, the Wanai-Suloga Peninsula, and possibly Nasai, were islands in a coral sea, for the coral limestone is superimposed upon these highlands ▲ 2 4

throughout the island. Since then denudation has modified the coastline, forming subsequent islands. There are. at present signs of subsidence on the southern, portions, of the island. There have been two principal periods of movement during which fissures were made into which metalli­ ferous and mineraliferous solutions were introduced. A general idea of the geology of the island may be obtained from a study of the geological map. It is impossible at present to exactly define the geological boundaries, there being only a ■ small portion of the island surveyed. The mineral-bearing country is characteristic, and can be traced in a north-easterly direction from the Wanai-Suloga Peninsula, being lost in the vicinity of Mount Kabat in the north-eastern coastline, Kulumadau Hill being an. outlier. This country consists of a reddish- brown decomposed porphyry and dark-coloured basic dyke rocks carrying mineral sulphide. Between the different mining centres the mineral-bear­ ing country is somewhat obscured by a thin veneer of coral limestone which should not be very difficult to penetrate. The alluvial deposits are found in the valleys between the Kulumadau Hill and the Okiduse Range, and on the eastern and south-eastern slopes of the latter. The following is a tabulated geological record of the rocks occurring on Murua :— Mangrove Swamps River Alluvium (gravels, sands, &c.) Recent. Estuarine Deposits Detrital Deposits (laterite, &c. ) Coral Limestone Deposit! Recent and Early ,, f'— Tertiary " (?) Sedimentary Slates 'i Deposits Limestones (in part meta- Conglomerates f Unknown. morphic) VV . Sandstones - J i Granite and Porphyry. Basic Eruptive Rocks (gabbro, dolerite, &c. ) Recent.—The low-lying swampy plains to the eastern and western ex­ tremes on Murua are broken at intervals by outcrops of the buff-colored coral limestone. On the southern coastline and for some distance inland the swamps are densely timbered with mangroves, the useful timber used almost entirely for fuel on the mines. There are a few elevated inland swamps, or grassy patches, as they are locally called, being sparsely tim­ bered with Pandanus trees. River deposits are met with in the Busai country and Muniai Valley, and consist essentially of gravel and sand beds with estuarine deposits carrying carbonised timber and fragments of shells. These beds have been dealt with in dealing with the Busai mining centre. The other deposits commonly met with, are more or less restricted to the mineral-bearing country, the mottled clays representing the weathered porphyry, and the dark brown or red laterite being the decomposition pro­ duct of the basic varieties of igneous rock. Recent and Tertiary ( ?).—There are two distinct varieties of limestone on Murua. The later deposits are buff-coloured and carry many fossils possessing a Tertiary and Recent facies. As this report is intended mainly for the economic aspects, a detailed examination has not been made of these or the earlier beds. The alluvial deposits rest immediately upon this limestone, which forms a shelf round the mineral-bearing country. It is by far the most prolific rock on the island, extending to the whole of the northern, eastern and south-eastern portions thereof. On the north-eastern portions of the island the deposit is represented by cliffs from 50 to 200 feet in height interrupted by stretehes of sand beach carrying coconut palms. A greater part of the western portion, and to a lesser degree the eastern extreme, the limestone occurs in the form of knolls surrounded by swamps. There are also numerous caves to be met with throughout, some of which are very beautiful, possessing those deposits commonly met with in cavernous countries, namely stalactites and stalagmites, &c. At Kulumadau, Bonagai, and on the track from Kara- vakum to Busai, the caves are large and unlimited in extent. The allu­ vium from the older rocks has been carried and deposited in some o f the water-ways in these caves, and prospects for gold have been obtained. These limestone beds, unlike the earlier beds, contain numerous Lamelli- branchs, Gastropods, and corals, &c. O f the earlier limestone deposits, little can be said. It occupies practi­ cally the whole of Nasai Island, and extends for a short distance across the gap on the eastern slopes of Kwagai Passage. On this portion of the coast there are cliffs and hills reaching a height of 600 feet, the country being very rough, consisting essentially of a series of minarettes and pin­ nacles of rock, and many caves. The rock is grey-coloured, carrying fossil remains more or less obscured by crystallization. It contains a few Lamellibrançhs, Gastropods, corals and Bryozoans. Sedimentary Metamorphic.— In dealing with these deposits reference will be made to the eruptive rocks occurring in their immediate neighbour­ hood. These rocks consist o f a series of indurated slates, limestone, sand­ stone, and conglomerates, and are seen to advantage oni the southern coast­ line of the Wanai-Suloga Peninsula, to a small extent on Nasai Island near Kwagai Village, and at intervals on the shores of Okiduse Bay. Leaving Suloga Point and going west we pass over a basic rock o f plutonic habit traversed by numerous pistachio-green colored veinlets o f epidote, and a few small dykes 12 inches to 18 inches wide, more acid 'n habit, and containing mica. The mass itself is rich in iron ores and on the saddle between Suloga Village and the Point, two holes have been sunk upon a deposit of micaceous Haematite and quartz veins, apparently associated with the eruptive rock. This rock extends toward Suloga Village, and is replaced by the porphyry near the old mining centre. It is also seen on Malpas Island and Usilas Point, and at both localities the iron ores and epidote occur. Passing on to Norac, a bluish-grey limestone is met with, partially metamorphosed, dipping N. 70 deg. W. at 25 deg. No fossils, as yet, have been seen in this rock, but an interesting cave carrying ossified frag­ ments o f human remains was discovered. It is probably an ancient burial- ground. The limestone can be traced over the hill and is ultimately lost, but is picked up again across Okiduse Bay. Passing from the limestone, we meet sandstone beds, with a few interbedded limestones near the base, where there is a holocrystalline dyke about five feet traversing it. Beyond this,, there is a thick series of fine-grained and coarse-grained conglome­ rates, slightly varying in strike but dipping at about the same angle as the limestone and sandstone. Between the limestone and the conglomerate and near to the top of ridge, a greenish-coloured, banded, silicified rock is met with. It is from this material that the natives make their stone adzes, and axes. Near Norac the conglomerate beds appear to rest upon a fine grained basic rock, in which are good thick deposits of magnetite and haematite containing much garnet and copper carbonates. These deposits are de­ scribed later. Beyond this more sedimentary beds are met with, which 6 pass under a swamp on the 'coast from Norac to Sililoi. On the top of the range in from the swamp, a medium-grained granite is met with con­ taining melanocratic phenocrysts. In the vicinity of Sililoi the sedi­ mentary beds are met with again, but consist of highly indurated sand­ stones and shales. They are intruded by basic dykes which have probably caused the metamorphism. At Sililoi there is an occurrence of the rock which occurs at Suloga and Norac, and containing the iron ores. Here there is a broad lode of garnet rock carrying veins and vugs of quartz and malachite. The sedimentary beds are continued to Kwagai Passage, and for a short distance west along the coast of Nasai. They are then re­ placed by a gabbroid rock carrying epidote veins, which passes beneath the high bluffs of limestone already referred to. At Wabana Point, oppo­ site Shoute Point, at the entrance of Okiduse Bay, the sedimentary beds again make their appearance and consist of sandstones interbedded with limestones and showing false bedding. T o the north of Shoute Point, laminated calcareous slates are to be seen at a point called by the natives Sosa. These extend inland and are met with on the south-eastern slopes of the Okiduse Range. From Wabana Point to The Bend there are out­ crops of sedimentary rocks in which the conglomerate beds again make their appearance. The conglomerates are again seen at PIayes’ Landing at the head of the bay. Granite and Porfhvyry.— These rocks are interesting in that they, par­ ticularly the porphyry, are of economic importance. The granite is fine­ grained, grey-colored, carrying sometimes biotite, and sometimes horn­ blende, or both as the dark-coloured constituents. It occurs along the main ridge of the Okiduse Range, on the divide between Wanai and the Ben, the various mining centres, and in an isolated occurrence at Granite Point, east of Malpas Island. This latter occurrence is interesting on account of the mass having been shattered at one time, and the interstices filled with a fine-grained oplitic rock more acid than the mass. The rock on the Okiduse Range and the Divide have been traversed by a few basic dykes and porphyries. Generally speaking, where these rocks occur they almost always carry auriferous bodies and veins of ore. They will be referred to in dealing with the various mining centres. Basic Igneous Rocks.— It is impossible to place on the map every occurrence of these rocks, except of course in the mining centre maps where as much detail as was possible was done. They1, possess in some cases a plutonio habit, but more usually are dyke-like in character. Some o f the fine grained varieties show a slight fluxional arrangement, but it is difficult, as yet, to accurately determine their exact nature without a petro­ logical examination. At Kulumadau, near the present mines, the rock is basic hypabyssal in habit, and beyond this, and the immediate neighbour­ hood, the true porphyry occurs traversed by fine-grained basic dykes. A similar rock occurs at Busai and its environs, which is dealt with later. At the entrance to Okiduse Bay and at intervals along the Southern coast line of the Wanai-Suloga Peninsula, the basic rock with a plutonic habit and gabbroid structure occurs, but has already been referred to under this sec­ tion. MINING CENTRES. Kulumadau.— Kalumadau is situated on a hill about 470 feet above sea level and i | miles from Bonagai, the Port of Entry on the northern extreme of Kwaipan Bay. The hill rises very abruptly above the sur­ rounding country, which consists of raised coral limestone densely covered with scrub. This limestone has been deposited even on the summit of the Kulumadau H ill, but most .of it has been denuded, thereby exposing the older rock which consists of a decomposed basic hypabyssal igneous rock, The hill trends north-east and south-west and gradually loses itself in the low-lying limestone country near Dekoias. About a mile frofn Kulumadau and situated on the north-western slopes of the hill is Waiakum, where a great deal o f alluvial work has and is being done. Here in the creeks, there are out-crops-of the older rock which carry gold associated with quartz and calcite. Since the discovery of Kulumadau a good many leases have been taken up and abandoned. Amongst the first were the Woodlark Island Proprie­ tary Company and the Ivanhoe Company. These subsequently sold out to the Kulumadau Gold Mining Company, Limited, which company is at present in existence. Kulumadau Mining Centre.— -The Murua Leases No. 40. These leases belonged to the Woodlark Island, Ivanhoe Company, Limited, no liability, and were taken up in the year 1900. It was primarily worked for alluvial and subsequently for reefs. Two semi-cross-cut tunnels, 70 and 100 feet respectively, were driven into the hill until they met. A shaft was also sunk away from the lode and a cross-cut of 80 feet from this to the lode made. The average thickness of the lode was 14 feet and yielded from .4 to 20 dwts. in 500 tons. Owing to the fact that this mine was not work­ ing at the time of my visit, and information scanty, I had difficulty in arriv­ ing at definite conclusions as to its wealth. Apparently it has not had a fair trial. The ore is good milling ore, similar to that on its neighbouring mine. In 1904 it was abandoned on account of water and want of capital. The mill lease was subsequently sold. The Kulumadau Gold Mining Company’s leases cover an area of about 120 acres, and comprise practically the whole of the remaining existing leases. This is the most developed mine on the island, and within later years a great many improvements have been made. Development work is going on both in the open cut and underground. Since the mine has been ..surveyed systematic tunnelling has been done, the former difficulties being eliminated. A new shaft is being sunk 100 feet south of present shaft. It passes through a dark coloured basic dyke rock near the surface, but with depth becomes much shattered and faulted with small veins of quartz and calcite with mineral. The present depth of the shaft is 405 feet, and is -being continued to the depth of No. 5 level, where it will be connected. A series of Huntington mills, W ilfrey tables, &c., comprise the mills. The cyanide plant is situated below the mill, and consists of four 50-ton leaching vats, two 15-ton mixers, and one 40-ton sump vat, &c. It is capable of treating 1,000 tons per month, and costs from 2s. 4d. to 2s. 6d. The sand assays from 2 dwts. 22 grs. to- 3 dwts. This plant is being duplicated to cope with the increased output. Until recently, no plans of the Kulumadau Gold Mining Company’s surface and underground workings were available. Use has. been made of what data there is, and a projection section and plans prepared. The lode has a north-north-east tendency, but is broken by a fault, and displaced to the north-west of the present shaft. Evidences of this fault are seen in levels 2 and 3 north by the presence of numerous slickensides and displacements. Breccia is present in the vicinity of the fault. The main Kulumadau lode is a large fissure vein in an igneous rock. The new shaft (No. 2) passes through this rock for 200 feet, and then into a fracture zone with veinlets. of quartz and calcite carrying mineral. There are five levels attached to the No. x shaft, which are being worked, with the exception of No. 5, stopped on account of water. The trial crushings from this level gave from 28 to 30 dwts. In the other levels very good 8 ore shoots have been met with. The results vary from 8 to 18 dwts., but" it is .a difficult matter to state exactly1 what the values are from the various levels, as only a few figures have been kèpt. The value of Kulumadau gold is ^3 8s. per oz. Waiakum.— At Waiakum, there has been a fair amount of work done and payable quantities of gold obtained. Being situated on the north-west slopes of Kulumadau H ill, much of the gold has been derived from the detritus products brought down by the creeks. In the creeks, there are small exposures of the gold-bearing country-rock possessing the same characteristics as that met with on the Kulumadau Company’s property. The creeks empty into' the limestone country, and take the form of under­ ground streams. In the vicinity of the dyke, there are evidences of metam- phoric sedimentary rocks. 'Of the remaining leases little can be said as there is little data concern­ ing them. On lease 32, now abandoned, is a, large lode of good looking stone, but from what I could gather, it only yielded 3 dwts. On lease 31, also abandoned, there are some veins carrying galena, yielding 1 oz. to ton. Ore Deposits.— The ore deposits of the Kulumadau district are interesting, in that the gold is associated with sulphides of iron, copper, lead* zinc, &c. Black oxide of manganese is frequently met with. The formation is a fissure containing much brecciated country rock and quartzite. This carries a high percentage of pyrites, and is traversed by numerous calcite and quartz veins, which latter have, in some cases, been very rich. In the Kulumadau Gold Mining Company’s No. 3 stope, an auriferous soft grey-coloured rock is being worked. It contains crystallized galena and zinc-blende, with a. minor proportion of pyrites embedded in a quartzose rock. Adjoining these veinlets the proportion of sulphides decreases gradually, and quartz grains become more prominent.

BUSAI MINING CENTRE. Busai is situated east-south-east about \\ miles from Kulumadau on the junction of the undulating limestone country, and older rocks on the north­ west portion of the Okiduse Range. Much alluvial gold was obtained here when first opened up at Coleman’s Creek, and even to the present day a good deal of alluvial is being worked. Notwithstanding the fact that some of the creeks have been worked several times, satisfactory results can yet be obtained from them. __ Not only in the creeks was gold discovered, but on elevated inland estuarine deposits, a great part o f which has been worked down to bed-rock. Here reefs were discovered in 1902, and several leases taken up, among the first being the Federation, Victory, Constance, and the Murua Syndicate; the Victory and Constance have both been abandoned. The Murua Teases.— These belong to a syndicate, and consist of the Murua No. 3, Kikit Vinai' No. 15, Guiau No. 4, and the Mary Marua No. 19, which have now been amalgamated to one lease— gold mining lease No. 84. There is a 5-head J-ton stamp battery on the property, driven by a 12-h.p. engine, and a 16-h.p. boiler; there is also a W ilfrey table and Berdan pan. This battery is well used, as it not only crushed the stone from the Murua leases, but also stone from the Busai leases. The Murua lease is situated on a hill which rises abruptly from Cole­ man’s Creek.. It is being costined extensively, and at the same time, its slopes are being worked for alluvial. Many reefs on adjacent properties trend in the direction opening up. Some of the Federation reefs can be traced partially through the property. On the south-western boundary is a healthy looking blue quartz lode, varying in thickness from' 6 to 15 feet, which has given some very satisfactory results. This lode was traced 9 practically the whole length of the Kikit Vinai, but on the north-western- extreme was lost beneath the alluvial and limestone. Shafts were sunk' through this alluvial with the object of picking the lode up again, but: these efforts proved fruitless. The southern extreme of lode passes into' the Busai Central for about 2 chains, where it is again lost, being cut off“ by à wall of decomposed porphyrite. At the southern end of the Busai Central a similar lode is picked up, traceable along the inner boundary of the Busai lease. It appears that, if this be the same lode, it has faultered with a horizontal displacement of about 100 feet. There are evidences of a faultered zone on the boundary of the Guiau and Busai, and from it two or three defined reefs, varying in thickness from 4 to 8 feet, and dipping at a high angle to the east, are met with, traceable to the blue quartz lodes on the Kikit Vinai, the largest lode on the property. The overburden of alluvial has been partly removed to a depth of from 30 to 40 feet, and in the north-western portion of the lease, a drive beneath this alluvial has been made, passing through boulders of porphyrite into a shattered and faultered country. Black pug veins are met with, together with irregular veins of quartz and calcite carrying mineral. Above this drive in the open cut a few small veins occurred, yielding from 4 to 50 ozs. amalgum per day (24 hours). The Kikit Vinai afford a good example of how the alluvial deposits; have been laid. In the sandy loam beneath the surface clay a stone pestle and mortar was unearthed in the early days, and in the black silt the- complete remains o f a crocodile. Throughout these deposits good prospects . have been obtained, the best gold being in the fluviatile deposits near the- base. Just above this deposit there is a swampy silt with numerous- carbonized stumps of trees, where gold likewise was found in payable quantities. The remaining portions of the Syndicate’s leases have been, and are- being, worked for alluvial. The next lease of importance is the Federation No. 2, and is situated;, north of the Syndicate leases; there are several good lodes on the property,., the results being most consistent throughout. Since 1905, 933 tons of ore- have been treated, yielding 1,610 ozs. of gold. This is especially good, when one has to consider the difficulties entailed in carrying the ore by hand a quarter of a mile to the mill. During the past year, a great deal of development work has been done, amongst the foremost of which, is the construction of a tramway from the lease to the mill. The tramway leads, directly to a tunnel 277 feet long, with an approach of 1,453 feet. At the end of the tunnel which cross-cuts the lodes, drives have been made, in which the lode material is being sloped. On the line of lode there is a main shaft, and a number of rises to the surface. The lode varies in width from 8 inches to 3 feet, dips with a high angle to the east-north­ east, and has well-defined walls. Above the lode, about 50 feet towards the hill, is another lode more or less parallel, and dipping in the same direction. Though fair prospects have been obtained from it, most of the work for the time is being devoted to the development of the main lode. It is quite probable that if the tunnel was continued it would cut the upper lode. Adjacent to the Federation are the Hub and Greentree leases ; but as these have only recently been taken up, little can be said about them. The Hub, No. 25, has three1 lines of reef passing through the property which give healthy prospects. Both reef and alluvial are being worked. One shaft was sunk on the Greentree, No. 12, which cuts a lode yielding fair' 10 stone, but has been temporarily abandoned on account of water. The lodes from the Federation can be traced north partly through the Green- tree leases Nos. i and 2, On the Greentree No. 1, a tunnel is being driven to intercept the iode from the Federation. The Vulcan (151) and the Vulcan South (26) are situated south-east of the Murua. There has been about 1,000 feet of driving and cross-cutting for reefs running north and south, with a westerly tendency, dipping in parts at a high angle to1 the east. The easterly reefs are more definite, but not so rich as the westerly. Most of this property has been deprived of its overburden of alluvial which carried gold. The thickness of reefs vary from 12 inches to 2 ft. 6 in. On the northern portion of the property, at the head of Elliot’s Creek, there are four drives running northerly 100 feet, north-easterly 180 feet, north-westerly 80 feet, and one leading towards the dam. These cut a few minor reefs and series of leaders. The results from the property are fairly consistent, a crushing of 104 tons yielding 101 ozs., the value of the gold being ^ 3 12s. Situated to> the east of the Vulcan leases, and partly running through the property, is Yank’s Gulley, in which a great deal of alluvial gold has been won. A great deal of the over-burden has been removed, thus expos­ ing a soft decomposed reddish-brown porphyry reticulated with veins o f quartz and oxide of iron. In the eastern side of the bank there is an ill- defined reef dipping irregularly and showing faulting. It has been pro­ spected, the results of which I could not obtain. The Busai No. 154.— This property carries a series of reefs and leaders. The former trend a little west o f north, and dip to the east at a high angle, except a reef on the eastern boundary, which dips westerly, and is about 9 feet wide. This is a probable continuation of the blue quartz lode passing through Kikit Vinai. Near the northern boundary of the property two shafts have been sunk about 40 feet to ground water-level, and cross-cuts and drives made from a small creek in the property. The stone carried) good looking mineral, and varies from 15 to 20 dwts. These reefs pass into the fault zone on the boundary of the Guiau and Busai leases, where there are remnants of old drives and shafts. The Busai Central No. 10.— This adjoins the Busai No. 154, and although the overburden is being removed and worked, the number of reefs exposed are at.present small. There are, however, numerous leaders trend­ ing east and west and dipping north, also a reticulating series of veinlets o f quartz and calcite in the decomposed porphyritic country rock. In the western angle of the property, where much o f the alluvial has been removed, good reefs are met with which are being worked. They are a continuation of the Busai reefs and the blue quartz lode from the K ikit Vinai. Lease No. 24, situated north of the Vulcan leases, has recently1 been taken up, and about 100 feet of driving and cross-cutting done. Four reefs have been cut, varying in thickness up to 12 inches, trending north and south, dipping irregularly at a high angle, and yielding a fair prospect. Faulting has evidently gone on, judging from surface features near the northern boundary of the property. The country rock is a porphyrite with veinlets of quartz carrying galena blende pyrites and gold. ■ The Constance No. 1, situated about half-a-mile south of the Busai leases, is now abandoned, and was worked mainly for alluvial. There are a. few leaders to be seen in the costines dipping at about 70 degrees to the north-west. The formation and reef material are not unlike that found on its neighbouring leases. There are also' a few basic dykes, more or less decomposed, to be found on the property. li

Ore Deposits.— The nature of the lodes, at Busai are analogous to those .-at Kulumadau, namely, the galena-quartz and the galena^calcite varieties, and in addition to these there are some fissure veins which almost entirely ■ consist of calcite and pyrites, and others again wholly of galena and pyrites with calcite veinlets. The calcite-pyrites veins are to be seen to advantage in the Federation and Kikit Vinai properties. They are fissure veins with secondary fracturing and enrichment. In the Federation we have the ^example pictured in the text, where primarily the rock was fissured, and iron pyrites with a small proportion, of chalcopyrite, and a veneer o f quartz, filling the cavities. The solutions modified the country rock, changing it almost into a sandstone with glistening specks of pvrites. Gold is obtained both from the sulphidic veins and the sandstone in the immediate neighbourhood. With subsequent movement more fracturing occurred, the fissures thus formed being filled with calcite and a small proportion of ■ quartz. In this particular specimen, no gold was seen with, the calcite; But there are, however, pure calcite veins containing a high percentage of gold. There is always a certain amount of the galena lode with veinlets ■ of quartz and calcite, which has given good returns. Throughout the lode formation, there is some rich vein-stuff carrying essentially, fragments of ■ quartz and country rock, subsequent veins of quartz carrying well-crvstal- lized sulphides, and splashes of galena, sphalerite and pyrites. Above the .ground water-level, green stains of copper made their appearance, together with oxide of iron. Here the gold can be seen in relief. Reilly’s Creek is situated about i mile south-east of Busai, and was worked extensively for alluvial in the early days. A number of leases were taken up and abandoned, with the exception of the Kauri Chief, which has recently been re-taken. It was in the vicinity of this lease, on a small creek running through the property, that the largest nugget yet found in Woodlark was unearthed; it weighed between n and 12 ozs. A great deal of coarse gold was taken out of this locality, but no record has been kept. North o f the track from Reilly’s Creek to McKenzie’s Creek, in a small tributary of the former, is a white quartzitic vein about 12 inches thick, very porous, and carrying mineral and gold. This rock is not unlike the Kulumadau stone, but differs in that there are numerous drusy quartz cavities. Near this locality, and just beneath the large alluvial face) there is a fine-looking galena lode trending north-east and south-east, and dipping at a high angle to the south-west. The foot wall of this lode is a doleritic rock, whilst the hanging wall possesses some of the features of the por­ phyry. The lode itself consists of saccharoidal quartz, with numerous veins of galena writh iron pyrites, and a little chalcopyrite. These veins vary from 1 to 5 inches in thickness, and carry a high percentage of silver. .An analysis made some years ago is as follows: — Gold 3 dwts. 6 grs. per ton. Silver 28 oz. 19 dwts. o grs. per ton. Lead 75 per cent. It is difficult to state extent of lode, as it has only been opened on .surface, but I see no reason why this lode should not be developed, as the ■ ore is a valuable one. McKenzie’s Creek is situated about a mile south-east of R eilly’s Creek, and was the first creek worked in this part of the country. The main feature about this locality is a steep open cut made some six years ago. After the alluvial capping had been removed, three shafts were sunk, and fhe open cut made on a rich lode about 15 feet thick, consisting essentially o f porous ferruginous quartz with mineral. At one part of the lode, there 12 is much decomposed, pyrites, and at another it passes imperceptibly into a decomposed formation o f porphyrite, carrying numerous veins of quartz and disseminated pyrites. It was in a rock of this description that rich pockets of gold were found. The general trend o f the lode is south-east, and dips to the north-east at a high angle, but it has become modified, by cross faults. The country in the vicinity of McKenzie’s Creek consists largely of a decomposed porphyrite traversed by numerous white quartz leaders, trending east and- west towards the lode. Close to McKenzie’s Creek are “ Skipper’s Gully,” and “ Scott's Creek.”' These are really small tributaries of McKenzie’s Creek, which latter empties itself into the Muniai River1 near Karavakum. Both Skipper’s and Scott’s Creeks are being worked for alluvial, though in the early days it was worked quite as extensively as McKenzie’s. The country in the vicinity of Skipper’s Gully is a schistose dolerite, with the plane of schistosity trending north-west and south-east ; it is crossed by small quartz leaders carrying sulphides and numerous veins of oxide of iron. I do not know of any work having been done on these leaders. The same rock is met with to a smaller extent in Scott’s Creek. There is a great deal of overburden of alluvial, which is at present being worked. The series of alluvial beds here are not widely different to those occurring at Busai, except that there are fewer fossil remains in the former, and evidences of inland swamps. The gold occurs in a medium conglomerate consisting of angular and sub-angular quartz and dolerite. The value of the gold from- this part of the district is ¿£3 or more per ounce. Sinkurai is situated about miles from Reilly’s Creek, on the head­ waters of the Sinkurai and Munkiai Rivers, on the south-eastern slopes of the northern portion of the Okiduse Range. A few leases were taken up in the. early days, but these have all been abandoned. They were- largely worked for alluvial, some very rich pockets of coarse gold being discovered. As much as 96 ozs., 84 ozs., and 72 ozs. have been taken from one pocket in Bains’ Creek, a small tributary of the Sinkurai River. There is yet plenty of scope for prospecting on the south-eastern slopes- of the Okiduse Range, as, during my sojourn in that part of the district, good prospects both in alluvial and reef deposits were obtained. Where- the alluvial has been removed, and in certain portions of the creek, a reddish decomposed porphyry is met with, and in a few instances, basic dykes, each carrying mineral, the former in the form of veins, and the- latter in small splashes. KARAVAKUM MINING CENTRE. Karavakum, or Bonivat, is situated south-south-east, between 6 and T miles by road from Kulumadau, on a small rise between the Muniai River on the north, and Thompson’s Creek to the south. Gold was first dis­ covered in New Chum’s Gully soon after the Okiduse and Sukoga dis­ coveries. A large quantity of gold was taken out of this gully, there being about 400 men on the spot. Karavakum, in my opinion, is likely to become one of the most im­ portant mining centres in Woodlark, there being a, permanent and interesting; series of lodes, from which good milling ore is being obtained. There are 24 leases, most of which are being worked with satisfactory results. The first leases taken up were “ The Towers Block,” now abandoned ; then “ The Illawarra ” and “ Woodlark King ” leases, which are being worked' at the present day, yielding, perhaps, some of the best returns of any of the single leases. It is difficult as yet to connect the northern lodes with» those in the southern leases, largely on account of the overburden of alluvial: and vegetation. 13

Notwithstanding the fact that the road was unfit to travel upon, the improvements during the last year have been a great boonsto Karavakum. Most, if not all, of the heavy machinery has been transported in punts up "the Muniai River or Thompson’s Creek. Amongst the latest improvements is a 25-head stamp battery on the Little McKenzie No. 1, and the erection o f a cyanide plant on the Woodlark King’s milling area, No. 12, together with rapid and enthusiastic prospecting for reef. Each working lease will be described, as far as possible, in order from north to south. Since writing this report, I understand that a good road has been made from Kulumadau to Karavakum. Little McKenzie No. 1 .— This property is situated in the most northerly portion of the Karavakum leases, taken up in 1910. A great deal of ■ development work has been done. Besides cutting an approach of 132 feet, there is a drive of 250 feet south to an underlay shaft 73 feet from : surface. The shaft was 12 feet by 12 feet, but is being extended along line of lode 12 feet more. A 25-head battery has been erected on the property, to be driven by a 45-h.p. engine. E'rying sheds are being erected, and a tram line from the mill to'the Mundai, a distance of a quarter of a mile. The lease was originally worked for alluvial; but when a small portion of the overburden was removed, the lode was discovered, which was worked with satisfactory results. A trial crushing of 23 tons yielded .40 ozs. of gold. The later crushings are as follow :— 33 tons yielded 227 ozs. 12 26 » 162 „ 0 30 „ 287 ,, 5 500 „ 332 „ 0

612 1048 17 The tailings are worth ¿Q6 per ton, and the average value of gold ^ 3 3s. per ounce. Gold can be seen without difficulty in the stone ; and. from the above results, one cannot help thinking this property will have a very bright Tuture. The lode itself trends north and south, with an underlie to the east at a 'high angle. It is a fissure lode in a doleritic country rock, adjoining porphyry more or less decomposed. The lode widens with depth, which is proved, by the several cross-cuts made. Near the entrance to the tunnel is a small reef or leader about 3 ft. 6 in. thick, trending south, 10 degrees -east, and dipping 67 degrees easterly. From this point on, the main lode gradually widens to 20 feet near base of shaft, where it meets a series of small veins coming in from the hanging wall country. Beyond this, -it “becomes irregular, and faulting partially obscures its movements ; but further driving has shown the faulting is small, and the lode has a tendency to widen to the south. The hanging wall country is largely composed of a dark fine-grained ■ eruptive rock, probably a basic dyke traversed by minute veins of calcite. The foot-wall country consists essentially of a semi-decomposed light-brown porphyry, with phenocrysts of a decomposed felspar. There is a large •extent of porphyry country on the Karavakum mineral belt. This porphyry again makes its appearance a few yards from the hanging wall, and is found in a creek near the eastern boundary. The real character o f the lode is somewhat analogous to the Busai •occurrence, but varies in some respects, in that there is a larger proportion of calcite and a considerable quantity of black oxide of manganese asso­ ciated with the gold. This latter occurrence is of interest in that some of .the richest specimens are obtained from it. It is known that the origin o f some of the manganese deposits is ascribed to the decomposition and leaching o f the country rock, but it is difficult at present to ascertain the- origin of this particular occurrence, as the existence of crystalline- manganese minerals is at present not known to exist in the country rock. Throughout the ore body there is a considerable quantity of fault- breccia' impregnated with sulphides, more particularly the iron sulphides, and numerous veins of quartz and calcite. Much o f the quartz is very porous and rich in sulphides and gold. Numerous drusy cavities of quartz are met with. The Little McKenzie South No. 2 is situated immediately south, and­ ad joining the Little McKenzie No. 1, and was taken up about the same- time. A considerable amount o f work has been done on this property, there being three 60-ft. shafts and three 30-ft. shafts sunk on the line of lode. There has been over 400 feet of tunnelling and cross-cutting, one drive being 260 feet along the line of lode from the southern boundary of the property. Stoping is anticipated in this level 70 feet from the surface. From two crushings of 70 tons, 105 ozs. o f gold was obtained, and I understand that there have been subsequent crushings, but the results, of these have not yet come to hand. The lode material is almost analo­ gous to that of the Little McKenzie, being a continuation of it, and can be traced right through the lease, underlying to the east. About 60 feet from the northern boundary the lode bifurcates, one branch continuing to* the south, and the other south-south-west, with an underlay east-south­ east. This latter again bifurcates, one arm parallel to the main lode, the- other continuing south-south-east. Between each of these lodes there are- series of veins and leaders, many of which are auriferous. Besides the development underground, a great deal of costining and alluvial has been done. The country-rock is a porphyry, with a few basic dykes traversing it. Near the south-west corner is another lode, which intercepts the former,, and passes into Brilliant Lease No. 14. This lode has an apparent width of 20 feet, and can be traced south 7 degrees east through the Little McKenzie (No. 2 South), and into the Moresby No. 4, where it is lost beneath alluvial. I have not heard of any crushihgs from this part of the- lode, but the stone is promising, and is being worked. Going east from No. 6 shaft, a series of leaders are met with, all yielding good prospects. These are in the vicinity of the main lode, trending a few degrees west of north, and cover a width of 12 feet. The Brilliant No. 14, the Little McKenzie (No, 2 South), and the Little Pete No. 9 are leases recently taken up, there being evidences of leaders and lode material on each similar to those on adjoining leases. The Moresby No. 4 is situated on the line of lode, and semi-enveloped by the Little McKenzie No. 2 South. There has been a considerable- amount o f alluvial work done here, nearly the whole of the cap o f the hill being removed for the purpose of isolating reef, &c. Though the over­ burden carries little gold, better prospects were obtained from the reefs through which deep costines were cut. There are evidences of the Little McKenzie lode on the north portion of the lease, but it is difficult to trace it on account of the overburden of alluvial ; however, g lode makes its appearance in Elliott’s Creek possessing similar characteristics to it, and may therefore be a continuation of it. It trends north and south at this point, and underlies at a high angle to the west, but the general tendency of the lode is north 20 degrees west through the property. The lode itself in the creek is about 12 feet wide, and consists of a greenish sand-rock (probably a decomposed igneous rock) containing well crystallized pyrites. A little to the east there is a small quartz reef more or less parallel to the- large lode, and about 3 feet wide. Good, coarse gold was obtained fren®, this reef, and on an average about 2J ozs. per ton from the large lode.. A great deal o f the gold is associated with a series of small quartz veinlets, occurring at intervals in the large lode, a recent crushing of 60 tons from- this property yielding 8| dwts. to the ton. In addition to quartz veins,., there are veins of galena and pyrites also carrying coarse gold. r* The lode in the southern portion of the property is lost under the' alluvial-, but is picked up in the Muriel and adjoining leases, recently taken up. It is again, lost under the alluvial in the “ Town H i!1 ” leases. Passing down Elliott’s Creek, a large quartz lode is met with dippr " north-east, associated with a considerable quantity of fault breccia,, traversed and cemented by calcite, and admixed with a high proportion' of crystalline sulphides. It was worked, in the early days, to some extent,, but I have not been able to obtain any information concerning the output from it. The “ Towers Hill ” (Syndicate) lease No. 3 is located immediately south of the Moresby and Little McKenzie No. 2 South, and adjoining the Muriel. This lease was taken up in October, 1910, and consists of 24 acres. The alluvial over-burden is being removed and worked. There are good indications of gold both in the alluvial and in reefs and leaders, which have been uncovered. The reefs and leaders consist of mineral- bearing quartz in a decomposed porphyritic country-rock, which is reticu­ lated with veinlets . of iron oxide, also carrying gold. The general trend', of the reefs and leaders is north 15 degrees west, underlying north 75. degrees east. The “ Golden Pig” No. 6, situated south of the Towers Hill lease,. was taken up in March, 1911. There are four lodes on the property, one- shaft 40 feet, and an open-cut and drive 40 feet. The lodes on the eastern, side of the lease trend north and south, and dip at a high angle to the east. The open-cut drive in the lode nearest the house passes through a series of veinlets of quartz and gold-bearing stone, which coalesces at a depth.. The lode has been displaced to a small extent by an east and west fault, which may be purely a landslip, as the workings are situated on. the side of a steep hill, and land slips are not uncommon in a place like Woodlark, where there is such a heavy rainfall. The race near the eastern boundary reveals a series of leaders in a decomposed porphyry. Near the western boundary there is a lode upon which a, shaft of 40 feet has been sunk, and at the bottom of the shaft drives approximately north and south have been made. The lode trends north 20 degrees west, and has a defined footwall of porphyry ; it has likewise been displaced, but is picked up along the- southern drives. On the surface, to the north, it turns to the north-east with a north­ west dip, traceable to the Towers lease No. 158 to the south, where it has been prospected and worked. The nature of the stone is not unlike that in the adjoining leases, there being a high percentage of galena and iron pyrites in certain veins, also black oxide of manganese. The stone is one- in which good prospects should be expected. The Towers No. 158 is situated south of the Golden Pig, adjoining the Waratah No. 5. There are two tunnels, 40 and 50 feet respectively, and one shaft, 40 feet, near the northern boundary on a reef about-1 foot thick and dipping to the south-west, which passes into the south-western corner of the Golden Pig. Passing easterly from the shaft and crossing a gully, there are a series of small leaders in a formation about 12 feet thick, which have yielded up tp 2-oz. prospects. They are probably connected with the lode passing from the Golden Pig. lb

Adjoining the Towers is a 6-acre lease, the Waratah No. 5, but no data is available concerning it, except that it has been prospected for alluvial. The “ Sunburst ” No. 16, which adjoins the Golden Pig on the one hand and the Namoharia on the other, is situated in the porphyry country, but has only recently been taken up. The Namoharia No. 10 is a 10-acre lease adjoining the Illawarra blocks to the north-east, and the Just-in-Time to the south-east, and was taken up in 19 11. A shaft has been sunk on the formation, and about 300 feet of trenching done. The reef, which trends a little west of north, is practically vertical, has a thickness of about 4 feet, and consists of quartz carrying sulphides and gold. There is also an east and west lode, ’in porphyry country, carrying a series of porous quartz veins, with a /thickness of about 30 feet, irregular dip, and yielding 7 to 12 dwts. The -shaft has been sunk close to the junction of the lodes, where good pros­ pects were obtained. The lode extends to the northern corner of the property, where it is about 1 foot thick, then passes through the Muriel lease, into the Illawarra Extended No. 150, where a shaft has been sunk on it. South of the present shaft it becomes irregular, but assumes its ■ normal direction again passing into a new lease called the Namoharia .(No. 2) No. h . Immediately east of the shaft there are a few reefs trending a little south of east, with a series of leaders between them, from which good prospects were obtained. The latest crushings from this pro- perty yielded 10 dwts. to the ton. The Namoharia (No. 2) No. 1 1 was taken up just prior to my departure. I cannot report on it, except that it is in porphyry country, which passes beneath the alluvial towards the southern boundary. The Illawarra Extended No. 150, Illawarra Consuls No. 163, Illa­ warra North 147, and the Illawarra No. 49, are leases which were taken up some time ago, and largely worked for alluvial. They are situated partly in the porphyry belt, and in the more recent alluvial deposits to the east. Near the Junction of the Illawarra Consuls and Illawarra North, there are series of small quartz and ironstone leaders in decomposed porphyry, which is met with in Reilly’s Gully. The data concerning these leases is wanting, and I am unable to report further on them, excepting the Illawarra No. 49, adjoining the Woodlark King' No. 48. Good gold has been obtained from' the alluvial, and payable reefs exposed. There is yet a good deal of gold to be won from alluvial in this lease, but owing to insufficient fall cannot at present be worked. This can probably be overcome by dredging, as the country is suitable for it. There is one shaft, 70 feet, on the property, situated near the south-eastern boundary, on a lode 15 to 20 feet wide, trending north-west'and south-east, and dip­ ping south-west. There has been 30 to 40 feet of driving done, and stoped nearly to the surface. The crushings of 300 tons yielded, on an average, 2 ozs. to the ton, and in one instance 80 tons yielded 4 ozs. to the ton. The country-rock is decomposed porphyry, traversed by a basic dyke seen in a creek passing through the property. The Woodlark King South No. 148 and the Woodlark King (No. 2 South) No>. 155 are leases situated south-east of the Woodlark King, the former adjoining it. Shafts have been sunk through over-burden of alluvial for isolating reefs, as it is known that reefs from the Woodlark King pass under this alluvial capping. The alluvial in the two leases can .'b e sluiced by directing the water from higher reaches of Thomson’s Creek «over the properties. The Woodlark King No. 48 is ah 8-acre lease south of the Illawarra. Tt was taken up in 1903, and. changed hands in 1906, and at the same Time a milling area of 3 acres adjoining the Just-in-Time was taken up. 17

The Woodlark King is one of the richest properties on the island. Since its commencement, over 2,000 tons have been treated, averaging 3 ozs. to the ton. The gold is valued at ^ 3 9s., and is very fine. Besides obtaining good results from reefs, there have been excellent returns from the alluvial. Nearly half the lease has been sluiced away, exposing reefs and lodes. A tram-line has been laid down from the Woodlark King to the mill. Eight shafts have been sunk, the deepest on the line of lode being 100 feet, others varying from 48 to 70 feet. The main lode trends north 50 degrees west, and south 50 degrees east, and underlies south 40 degrees west at a high angle. It varies in thickness from a few feet up to 50 feet near the north-western boundary. One shaft, 70 feet, on the boundary passes through similar formation, and has yielded good prospects. Near the southern portion of the property, in a reef off the main body, another shaft of 67 feet is sunk. These two shafts are connected by two levels, and have yielded some very rich stone. Between the house and the tram­ line a shaft has been sunk through the alluvial. Formation was met with, and a lode about 15 feet wide, dipping south-west, together with a series of ferruginous quartz leaders. This lode formation, which trends north­ west, appears to meet the large lode outside the north-western boundary of the Woodlark King, between the shafts, It is traceable over the tram­ line, and is seen in a small cutting near the south-western boundary. Some of the shafts from which rich stone was obtained have been tem­ porarily abandoned on account of water troubles, but an adit is being made which will probably obviate this difficulty. The formation as a whole consists of decomposed fragments of country- rock, in which occur veins of saccharoidal and porous quartz, containing mineral and carrying gold. There are also numerous intercalating veinlets of iron oxide, carrying gold. The country-rock is porphyry, traversed by basic dykes, which are seen in a small creek passing from the Wood­ lark King into the Illawarra, the Just-in-Time, and in Thompson’s Creek. The Just-in-Time Lease No. 146 is situated immediately south of the Woodlark King, and has been costined to a depth of 20 feet or more, exposing country. The alluvial is characteristic in part to the other occur­ rences on the island, there being a considerable thickness of estuarine silt, carrying fossil remains and carbonised timber. Super-imposed on this there is a coarse gravel in a sandy matrix, which carries alluvial gold. In a small creek on the southern portion of the property, and in the vicinity ò f the costines, the decomposed country reticulated with iron oxide veins and calcite are seen j also a basic dyke rock. In the creek running parallel With the tram-line, a series of small veins are seen in similar country, A hard bar o f rock also occurs here, but cannot be traced on account of the alluvial over-burden. The Tickler No. 8, adjoining the Just-in-Time, and the Unknown No. 7, adjoining the northern boundary of the Woocllark King, have lately been surveyed, the former recently taken up, and the latter some time ago. Both leases are capped with deep alluvial of the same nature as the neigh­ bouring leases. A shaft has been sunk through the alluvial near the resi­ dential area on the Unknown on the continuation of the cross-reefs of the Woodlark King, but I do not know the returns from it. In Thomson’s Creek situated south of the Karavakum leases, and which fiows easterly from the Okiduse Range, the decomposed porphyiy is seen with a few basic dykes more or less diabasic in character, together with indications of mineral-bearing formations. Theye out-crops are lost under the alluvial on either side and in the mangrove swamps to the south-west. Ç.10048. B Most of the mineral-bearing country on the Karavakum-Boniavat rise pass under either the coral limestone or the swampy alluvial. Outcrops occur at intervals in the Nuniai river near to where the tracks cross the fiver, in going from Karavakum to Busai. Situated to the north of the Little McKenzie is a prospecting area, where are three deep races in the alluvial. A small creek flows through the pro­ perty in which the porphyry and a basic dyke are seen, but ultimately passes under the limestone. The Okiduse Mining Centre is situated south of Karavakum on top of a spur. Alluvial claims were taken up and good gold obtained in the early days, but only one claim is being worked at present. Good looking reefs have been exposed, in which gold can be seen. They trend north 55 degrees ■ west and dip south 35 degrees west, and are in a grey coloured porphyry, which is altered to a reddish-brown colour in the vicinity of the veins. Where the alluvial has been worked are strong outcrops of porphyry. This extends and can be followed on the track from Okiduse to Karavakum, and for a short distance towards Hayes’ Landing. Near the top of the ridge passing from Karavakum to Okiduse is an outcrop of dark coloured igneous rock resemblin|g a diabase ' dyke, which readily weathers to a reddish-brown laterite. The Ben, named after a creek in the vicinity, is situated on the western shores of Okiduse Bay, was worked exclusively some fifteen years ago for alluvial. Though good gold was obtained it was abandoned on account of other localities on the island being discovered and boomed. It is now worked under the name of the Consolidated Hydraulic Sluicing Claim, and yields 15 ozs. per month per man. The country in the vicinity is apparently rich in alluvial, the exposed portions consisting essentially of red or mottled clay traversed by a few broken quartz and ironstone leaders. The subsoil almost always carries good gold, but beneath it, in the finer gravels, gold occurs in runs. Beneath this are large boulders of country rock partly water worn and decomposed. Many unweathered boulders carry sulphides, and appear to be connected with basic dykes passing through the porphyry. One of these large bars is situated near the house and consists of augite phenocrysts. In some respects these rocks resemble lavas, but a petrographical examination is necessary before being named. The Ben field is situated on flat country beneath a range of hills 1,000 feet high, from which probably most of the alluvial gold has been shed. The Suloga Centre, situated a mile north of Suloga Point, has been worked extensively in the early days for alluvial, and very coarse, water- worn gold won. It was reported to me that a 12-oz. nugget was unearthed in this locality at the time of the rush. The alluvial is still being worked, particularly towards the head of Suloga Creek. Four leases were taken up, known as the Eureka Blocks, since abandoned, and although the alluvial in the neighbourhood of the leases has been almost removed there is yet scope for. further work on the surrounding rises and gullies. There are numerous white quartz leaders in a brownish-red, mottled formation on leases where the alluvial has been removed, but little or no work done on them, being barren on the surface. The Wonai Centre is situated on a spur on the southern shore line of Wonai Bay. There is one lease and a sluicing claim situated on the Wonai Creek. The alluvial at present is payable, the deposit consisting of an ad­ mixture of boulders of igneous rock, quartz, and slate embedded in reddish- brown clay. Near the house this deposit rests upon a soft blue clay, which is the altered portions of a clay slate and is, in part, indurated and traversed 19

by quartz veins. Associated with the slate are bands of quartzite carrying pyrites. The sedimentary rocks are highly metamorphosed, due to the num­ ber of basic dykes in the vicinity. False bedding and lamination is some­ times seen in the less disturbed country. Going up a small creek a little south of west from the claim, and situ­ ated on the rise, is the Wonai lease. The country in the vicinity is very rough, and consists of mineral-bearing formation, a few metamorphic sedi­ ment, and a large basic dyke, or series of dykes, which have weathered into boulders ten yards or more in diameter The outcrop is very pronounced about half-way up the hill. Though good gold was obtained here in the small creek, work was tedious owing to the number of large superimposed boulders. It was whilst working in this creek that floaters of ferruginous quartz were found carrying gold, and, late in 1911, the Wonai reefs were dis­ covered. There are four distinct reefs in a soft, ferruginous, sandy rock strongly laminated in part and broken up considerably. It is evidently the results of faulting, the fault material re-cementing the dislocated fragments. A little to the north is a small outcrop of metamorphic sedimentary rocks, consisting of indurated slates with inter-bedded sandstone. Between this and the reefs is a basic dyke penetrating the sedimentaries and lode. The reefs can be traced for some distance and appear to be permanent. Gold can be seen without difficulty in every piece of reef stone, the best stone being a pumaceous quartz with veins of pyrites. Besides the main reefs there are numerous quartz veinlets all carrying gold. Sililoi and Norac are two interesting localities situated on the southern coast line of the Wonai-Suloga Peninsula, the former about 2 miles from Kwagai, and the latter about miles from Suloga Point. The country in the vicinity consists essentially of metamor phic sedimentary rock intruded by basic dykes. In the vicinity of the fine-grained varieties of dykes, and at the above localities, there are large deposits of ironstone (magnetic) asso­ ciated with copper carbonates, garnet-rock, and many well crystallized quartz- veins and vugs. About a quarter of a mile up the Sililoi Creek, a large, irregular, massive deposit of yellowish-brown garnet occurs, containing numerous vugs of well crystallized quartz and micaceous haematite. Several well formed crystals of garnet were collected, the principal forms being the Roambic Dodecahedron and Trisoctahedron. Immediately above the garnet, the magnetite deposit occurs, containing a considerable quantity of copper carbonate in the form of beautiful Malachite needles. These are usually in small vugs containing well crystallized quartz. Garnet also occurs in the mass. The magnetite crystals show the development of the octahedron and cube. In the weathered portions of the mass, the rock has a bright yellowish appearance, the garnets standing in relief. In close proximity to these deposits there are basic dykes carrying splashes of mineral; and highly indurated sedimentary rocks. The occurrence of Norac is almost analogous, there being a greater quan­ tity of iron-ore in sight and a higher percentage of copper. In the vicinity of both localities, it is of interest to know that quartz leaders carrying gold occur.

By Authority : A lbert J. Mullett, Acting Government Printer, Melbourne. QUEENSLAND UNIVERSITY LIBRARY 152^ 30 ' 152* 4 5 ' 153^ P L A T E 2.

GEOLOGICAL SKETCH MAP

OF KULUMADAU MINING CENTRE,

E v a k t 33.. ST-A.isriiL.iE'sr,

GOVERNMENT GEOLOGIST,

1 9 1 2 .

20 30 _i_ j . Chains

Alluvial and Limestone Porphyry

Dolente, âc.

Lodes and Reefs Existing Leases— r .. . Extinct i___ __ Tracks-^ ___- ~ ~ -

Geological Boundaries PLATE 3.

GEOLOGICAL SKETCH MAP E ZSIE3 3L A.T T A . T I O TV. OF Alluvial BUSAI MINING CENTRE, Coral Limestone BY .'V Porphyry E van IR. Stanley, V* GOVERNMENT GEOLOGIST, 'Basic Dykes 1012 . . Lodes and Reefs Leaders ////

Shafts m Faults Tracks PLATE 4.