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VOL. 46 MAY 2000 NO. 2
The 3iorefield Pegmatite, Amelia, Virginia. Mineral Update bv Lance E. Kearns Department of Geology and Env~ronmentalStudie~ James Madiqon Cniversity Harrisonburg. VA. 11807 and Betsy S. Xiartin 3166 Sherhrook Rd. Richmond. VA. 13135 Six additional mineral species have been iden- orthorhombic forms f I I I 1. ( 1 10). and are modi- tified from the Morefield Pegmatite near Amelia, fied by a well developed (010) pinacoid (Fig-
Virginia. Fluellite, A1 (PO )F (OH) • 7H 0; ure 1 ). The Morefield occurrence represents the bismutite. Bi (CO )O ;hollahite. ba?~n'-~~n~-)0 : third U.S. locality along with the Carolina Pyro- phyllite Mine, Randolph County, North Carolina cerussite P~COI &arksutite. CaAI(0H)F .h 6 1, (Dunn, 1977), and the Gold Quarry Mine, Eureka and brockite ((2.;. Th. Ce)(PO ) H 0 have been -1- County, Nevada (Jensen et al., 1995). identified by X-ray diffraction and further veri- Fluellite was originally discovered at Stenna fied by semi-quantitative Energy Dispersive G\\y, Cornwall ,England. and later at Kreuzberg, Analysis (EDAX). Euhedral crystals of prosopite Bavaria Germany. The German material was named have been found and photo_mphed for the first time kreuzbergite. Fluellite and kreuzbergite were proven from the Morefield Mine. Light blue. cobalt blue, to be the same mineral. and the name krembergite and purple apatite crystals are abundantly present was dropped. The original composition was not ac- in southwest workings of the mine. curately determined it was originally believed to be a hydrated aluminum fluoride (Palache et al., 195 1). Fluellite: A I (PO )F (OH) 7H 0 Guy and Jeftkey (1 966) found the presence of essen- 2 3: tial phosphate during the structural determination. Fluellite is a rare, secondary aluminum phos- phate, which forms as an alteration product of trip- Bismutite: Bi /CO jO * 7, lite (Mn'?, Fe-" Mg. Ca)(PO )(F,OH). It occurs J in small vugs with triplite, bermanite. strengite. Bismutite occurs as masses, smooth crusts, and and spherules of opal-like material. Crystals are aggegates of opaque, rough needles up to 0.1 mm small (0.5 mm). colorless and transparent, with (Figure 7). Individual crystals are light yellow- 10 VIRGIKIA DIVISTOY OF MIKERAL RESOURCES VOL. 36
broken pieces. Solid masses often show textured, flat surfaces which develop when formed between plates of cleavelandite albite. These flat surfaces are often iridescent. Botryoidal surfaces form in open cavities. and. stalactitic forms are obsen-ed bndgi ng lugs. HoFlandite is found with albite (cleavelandite), quartz. microcline (amazonite), and bismutite. Apa- tite masses frequently coat the hoIlanditc. Pyro- rnorphite and apatite crystals occur in rwgs. v-, Figure : ,~.~cll~tcCQ -tal \r~tl~~~.=nnaniri. (prismat~c1. and spheres of opaline material. SEM Photo. Gearksutite is the eighth alumino-fluoride mineral species to be recognized from the Morefield PC-ma- ish-tan while masses and crusts run from tan to an tite. It is found as chaIk white masses and mats com- intense yellow with a rvaxy. dull. or resinous lus- po5ed of very fine needle-like cystals. Mats of ter. Cmsts and cpstals are associated with cas- -vearksutite are generally found in and around siterite. albite. tantalite, zircon. hollandite, prosopite masses and c~stals.The presence of rnicrolite. and monazite. searksutite at the Morefield Pe-matite has been an- Bismutite is a secondary bismuth carbonate ticipated. It is characteristically associated with simi- xvhich generally forms from alteration of lar aIumino-fluoride assemblages found at other TO- bismuthinite or other primary bismuth minerals. lite bearing pematites like. Iz-i_mt. Greenland: St. Findings suggest that bismutite is widespread Peter's Dome. Colorado: and the Zapot Pe-matite in throughout the mine as a late stage alteration prod- Vineral County. Nevada. uct. Other bismuth bearing minerals have not been identified from the Morefield Pegmatite.
Figure 3: Gearksutite. SEM photo. Figure 2: Bismutite crystals. SEM photo
has col- Hollandite is found as small. black. botrq.oidal One of the authors (B.S.M.) rcccntly masses (up to 10 rnml. and bright. silr~ery-black. lected numerous samples of cerussitc from the heavy mineral fraction of the northeast adit floor. \'irg~n~a\l~neralc. 1'06 46. Yo 2. May 2OOO NO. 2 VIRGISIA MINERALS 11
The crystals (up to 2 m)are adamantine, transpar- ent. and hvinned. Most specimens with matrix are associated with pyomorphite and, less commonly7 with mall clear apatite crystals. Qne specimen shows cerussite crystals on galena with yellowish green pymmorphite crystals. Specimens from the alumin* fluoride area show cerussite with galena. Cerussite has also been noted in the southwest adit. Glass ( 1935) previously reported the occur- rence ofcerussite from the nearby Rutherford peg- matite, but did not credit ot reference the identifi- cation. Sinkankas (1 968), did not include cerus- site in his discussion ofminerals from the Ruther- Figure 4: Energy Dispersive X-ray Analysis of ford Pegmatite. This is the fjrst known verifica- ye1 lowish-orange brockite. tion of cerussite from the Morefield Pe-matire. tified fr~mthe Morefield Pe_matite (Kearns. 1992) as a Iavender-gray. massive material. The first euhedral crystals have recently been identif ed as Brockite is an uncommon member of the shown in Figure 5. The crystal habit is similar to rhabdophane group. The me material was origi- those reported from St. Peters Dome, Colorado nally described from the Bassick Mine, let Moun- and illustrated in Palache er al. (1 95 1) tains. Custer County, Colorado in a similar min- eral assemblage of quartz, atbite. apatite, and he- matite. The species was named in 1962 in honor of Maurice Brock of the U.S. Geological Survey. The Morefield Mine material occurs as fag- ments and intact masses up to approximately 1 cm. in size. It is very fine grained. with a greasy to resinous luster, and conchoidal hcture. The color ranges from mottled reddish-brown to a solid yel- lowish- orange. the Tatter being translucent. Rrockite is highly radioactive due to its hish tho- rium content. EDAX analysis ofthe darker, reddish-brou-n ma- terial shows a significant Fe content (hematite inclu- sions) that is absent from the translucent. yellowish orange material. The analysis of a yellowish or- Figure 5: Prosopite Crystals. SEM Photo. ange sample (Figure 4) sho~ssCe as the major rare earth element. Concentrations of other rare earth el- Anatite: Ca (PO,.: ) tOH,CI, F) ements ~verenot ptenough to be detected by EDAX analysis. Analyses show that some material has mi- A number of small, well formed. purple. and light nor amounts of Si substituting for P. blue to cobalt blue apatite cystals have been re- covered from the southwest end of the mine. These Prosupite: CaA J (15OH) crystals have complex terminations (Figure 6). They are also striated and color zoned. Individual Prosopite. CaAI (F.OH) . was previously iden- crystals have been reported up to I cm. in size but 12 VIRGWIA DIVISION OF MIYERAL RESOURCES VOL. 46 are more commonly 1 to 3 mm. They fluoresce was pumped down to 87 feet below the shaft GOE- golden yellow in both LW and SW ~Itraviollezlight. lar (42 feet below the floor of the 45-foot adit). . Mitchell and McGavock (1 960) suggest the fluo- This is the first time this area has been exposed rescent activator is manganese, and is present from since the U.S. Bureau of Mines terminated its ac- 2 to 2 percent by weight. tivities in 1948. Mud and iron stains on the shaft walls prevented detailed observation of mineral- ization. There appears to be about 1 8 to 19 feet of debris accumulated at the bottom of the shaft. Mr. Dunaway hopes to remove this material in late fall 1999 or spring 2000. Minor excavation for the northeast end is in the plans for the year 2000. Extensive mine production and refurbishing have also been completed. The underground lighting sys- tem has been up_mded with disconnect boxes and in-use covers for shock protection. Large 18-inch air circulation ducts have been installed for more ef- ficient removal of smoke and radon. A two-inch Figure 5. Apatite crystal showing complex terrni- steel compressed air line has been installed down nation. SEM photo. the shaft to get more air to the drills.
PROGRESS OF RECENT MINING ACTIVITIES We are, as always, indebted to Sam and Sharon Sam Dunaway, owner and operator of the Dunaway, owners and operators of the Morefield Morefield Mine, has been actively mining toward Mine, and to its previous owner, the late Wm. the southwest end of the pe_matite. Presently "Bill" Baltzley. who provided these samples for (Dec., 1999) the southwest mine face at the 45 foot analysis. Without their trust and enthusiasm, this level is 160 feet southwest of the original work and previous mineralogical discoveries at Morefield shaft. During 1998 and most of 1999, the Morefield Pe-patite would never have been very little high quality amazonite was encountered possible. We also wish to thank Stan Rudis of Rich- in this area, but good cleavelandite, monazite, tan- mond and Dennis McClevey of Fredricksbuq, Vir- talite, and muscovite were found. In July of 1999, ginia for their hard work in screening the samples the adit passed through the site of a diamond drill used by the authors. hole, drilled by Martin Marrietta Corp. for the former owner of the mine, the late William 'Bill" REFERENCES: Baltzley. Water was flowing from the old drill Dunn. P.. 1977. Ftuellite from Xoflh Carolina .\Iin~rulog~cnlRecord. %. 8. p hole at a rate of 3.75 gallonslminute. necore .??2-.?93. fkom this hole did not show the mineralization that Food. E. E.. Soregaroli. A E . and Gordon H. \+..1W.Th.e 72pt pa- was hoped for. It missed rich masses of amazo- tlte. Mineral Count).. hevatfa: Mlneralo~lcaiRecord.K. 30. p. l---291 nite, cleavelandite, and apatite crystals by only a Glass. J.. 1935. The pputltem~ncrals from near Amelia VITI~I~Amencan few inches. In August, 1999, the southwest adit M~nc,ra/oprrt.v. 20. p 4 1.76- encountered an apparent shift (fault?) in the peg- Guy. B. R.. and JefSrcy G. A..1966. The cpstal structure of flucllitc. matite. Beyond this point a new area rich in high .41 (PO )f (OH) fHAO:.4mericnn.Wineralo~i.r!,v.5l.p. 1579-1592. quality amazonite, mica crystals, and heavy min- I1I 4ensen. M. C.. Rota. J C .and Foord. E E .I'M!. The Gold Quarry Mine. erals was encountered. Carlin-Trend. Eureka Counw. Vex ada Wlneralnercal Rerod i.16. p W9- During the spring of 1999, the Morefield shaft 459
Viginia Minerals. Vol. 46. Yo. 2,May 2000 NO. 2 VIRGINIA MNERALS 13
Keam5. L.F... 1993. Alumino-fluoride minerals from the Sforefield \line: Palache. C.. Rerman. H.. and Frondel. C.. 1951. Dana's System ofMineral- livinro .Ilinerolr. v. 39. p. IS. 09.Vol. 11: John \file? and Sons. Seu-York. p. 121-123.
Keams. L.E.. 1992. Prosopite from the Moretield Mine. Amelia County. Sinkankas. J.. 1968. Classic mineral occurrences: geolop and mineralogy i'irzinia: Iirpinia .Minerals. v. 38. p 14. of the Rutherford pegmatires. Amelia \i~inia:Amrrirun .\frneralo~is?.\. 3.p. 3'3 -405. \litchell. R.S..and SlcGavock. E. H.. 1960. Apatite from the \Torefield Pez- matlte. AmeliaCount?: ii~inia:Rmk~ andrlljnerol~. r 35. p. 552-554.
VIRGINIA GEOLOGIC CROSSWORD PUZZLE '? Roy S. Sites. VDMR
I. \i~n~a'sktknoun salmon-pink and pxneemnrk . The ppe oftemln charactrrizcd h) sinks and sinkholeq occurring throughout the u.wtem pnlon ofrhe State. 2. A t?pofrock _eenerall\ formed fromother rock5 being tranqmned and de- pm~tedIn aater 8 \fan) \'iqnlan> indulge In th~rhobby utlllztng the man! mkc.m~neralr.and _rcm~tonfifound throughout the \tart 3. .4 cm-pined rock containrng many meminenlsoxurring in the \?nrcficld Vine of Amelia Ccjunt? and s~mulsttdIn the Sml~hwnianRocks and Wlnenl 9. \'irginia's moct baluahlc mincral recource. occurring pnnclpall! throughout exhihit southwtxm \i~nia'cPlateaus Pm\ince.
1 The long narrow mountaln cham trcndtng northeaxt-southue 5. The liquid hydrocarbon king pumpcd fmm nellsdrilled principally in Lec I I. Rocks fonned hy thesolidrfication froma molten state: thcce rocksarecom- Counn. is called -, mon thrnughout the Blue Ridge and P~edmonrponionsof the State. i'iginia Minerals. Vol. 46. No. 2. May 2000 Postmaster: Virginia Minerals Send address corrections to: Second-Class postage paid at Virginia Division of Mineral Resources Charlottesville. VA P. 0. Box 3667 ISSN0042-6652 Charlottcsville, VA 22903 JJ Mined from man) \i~rn~aca\edunngthe\Varof1812 andthcC 1\11 Nar. M1 T~IF'oft. gcncmll:. uhrre rn~nmluac mrned near LWIIC~Cole ~n Sm!fh \itplnrd u ac uuxi In rnahrng Fnrnuder Counn. and 1s 3 prlnclple lngedtent ucrd In Plahterof Pan\ and manufactunln uallhd 45. Mdern-day prospecting enthuslaas still wwder along thecreeks of\itplnra's Piedmont her. the! LITihc elusr\ e preoous !cl!ou metal: some \\ ~th 61 \Itned from the Old II~ckor.dcpslt In D~nulddttCount>. thccc ~anous F1success. hem? mtnenl Liptnla', rock h\rmart 50. Those mhutan streams. generally with steep gndients. wrthin the upper reachm ofa dratndgebasrn, anc: In u hrch caTthe larper fnpmentc ofuearhered rwk tbrrnatlons.nri. referred to 3.; the ----\\aten of thzt dmtnage ha~in 5 1. The most common rn~nmlfound in Uqinra. It 1s the marn concrltunt of tu o VIRGINIA MIiVERA LS ON THEW'E B rwkz: I~mt?%tneandmarble. It commonlynvcum In c3\ edepm~re.And. thepecu- llar .'clam geode,.' frrlm C'he\apcaLc and \'lratnr3 Hc3ch are l~nedu~rh cryitalr. Beginning with the February 2000 issue, I+- 52. \icnt geologistsape that \irginia hac not undcrgcmedimt effrns ofth~sAge. ginia Minerals will be available on the but wrth~nrhr. h~ghcrclexatt~mso: thcOl~i I)orn~n~on therearea t'ru featurmtLlnt mayretlect a reyvnce tothe harrh cltmatedunne the -:\ge. INTERNET at ~w~v.geology.state.va.us.Printed 53. Thmughcwt \iq~nraah-wen mm! m~lic~allyplaced m= Y. Throughout \irginla -merally tn now fimtdarm%. tkT arecovend mounds of a wmct~me$mulrt-colored \~rmu 55. Voted by Tbomac JeFmon in 1R?5. and a111vi5ihle today from L'.S Irish- may 220 In Allcghany Counr): arc the ucll knoun -n-t;>ot Falls of Fall~ng The answer to the crossword puzzle will ap- pear in the August 2000 issue of Uqinia ,Viner- 56 French word for watc als and will be available on the Web paee at C- 4 recordand graph~cpreqentatton of rwh fc~rmatlon\vnetratsd b? a ucll- bore In dn[Ilnp tor h\drcrartnn- oruaterare hnoun a- a of !bat \\ ell u~~wGgeo1ogy.state.va.u~. 5%. The lest~ubdi\ ision ofgeologic time. Thmare basically three recqmi7ed grand d~v~c~oncoft!me:each calldan -. 59. Thmughou~Un$nia. pnicularly in thc\illey and Ridge. compmsi\ e forcer har cdefonnedand ddriton~xirltnta Into \arious hc~d.and undui3ttnn\ cc>mmonl! refcrrd to 3, \'iqinia 3finerals. Vbl. 46. So. 2. May 2000