Zeolites in Tasmania
Total Page:16
File Type:pdf, Size:1020Kb
Mineral Resources Tasmania Tasmanian Geological Survey Record 1997/07 Tasmania Zeolites in Tasmania by R. S. Bottrill and J. L. Everard CONTENTS INTRODUCTION ……………………………………………………………………… 2 USES …………………………………………………………………………………… 2 ECONOMIC SIGNIFICANCE …………………………………………………………… 2 GEOLOGICAL OCCURRENCES ………………………………………………………… 2 TASMANIAN OCCURRENCES ………………………………………………………… 4 Devonian ………………………………………………………………………… 4 Permo-Triassic …………………………………………………………………… 4 Jurassic …………………………………………………………………………… 4 Cretaceous ………………………………………………………………………… 5 Tertiary …………………………………………………………………………… 5 EXPLORATION FOR ZEOLITES IN TASMANIA ………………………………………… 6 RESOURCE POTENTIAL ……………………………………………………………… 6 MINERAL OCCURRENCES …………………………………………………………… 7 Analcime (Analcite) NaAlSi2O6.H2O ……………………………………………… 7 Chabazite (Ca,Na2,K2)Al2Si4O12.6H2O …………………………………………… 7 Clinoptilolite (Ca,Na2,K2)2-3Al5Si13O36.12H2O ……………………………………… 7 Gismondine Ca2Al4Si4O16.9H2O …………………………………………………… 7 Gmelinite (Na2Ca)Al2Si4O12.6H2O7 ……………………………………………… 7 Gonnardite Na2CaAl5Si5O20.6H2O ………………………………………………… 10 Herschelite (Na,Ca,K)Al2Si4O12.6H2O……………………………………………… 10 Heulandite (Ca,Na2,K2)2-3Al5Si13O36.12H2O ……………………………………… 10 Laumontite CaAl2Si4O12.4H2O …………………………………………………… 10 Levyne (Ca2.5,Na)Al6Si12O36.6H2O ………………………………………………… 10 Mesolite Na2Ca2(Al6Si9O30).8H2O ………………………………………………… 10 Mordenite K2.8Na1.5Ca2(Al9Si39O96).29H2O ………………………………………… 10 Natrolite Na2(Al2Si3O10).2H2O …………………………………………………… 10 Phillipsite (Ca,Na,K)3Al3Si5O16.6H2O ……………………………………………… 11 Scolecite CaAl2Si3O10.3H20 ……………………………………………………… 11 Stellerite (Ca,Na2,K2) Al2Si7O18.7H2O……………………………………………… 11 Stilbite (Ca,Na2,K2) Al2Si7O18.7H2O ……………………………………………… 11 Tetranatrolite Na2(Al2Si3O10).2H2O ……………………………………………… 11 Thomsonite NaCa2[(Al,Si)5O10]2.6H2O …………………………………………… 11 Wairakite CaAl2Si4O12.2H2O ……………………………………………………… 12 REFERENCES ………………………………………………………………………… 12 Tasmanian Geological Survey Record 1997/07 1 Ab stract The zeolites are a ‘supergroup’ of aluminosilicate minerals, and natural deposits are of diverse style and may be of considerable economic significance. Nineteen different species are known to occur in Tasmania (including Macquarie Island), and the major occurrences are briefly described. The host rocks are mostly Tertiary basaltic rocks, but also include dolerite, mudstone, sandstone, granite, quartz veins, skarns and other rock types. Styles include veins, replacement, pore filling, breccia fill and vesicle fill. Economic deposits are not currently known in Tasmania, but there are numerous small occurrences, some of which are relatively rich and of moderate size, giving indications of some potential for economic mineralisation. Very little exploration for zeolites has, however, been undertaken in this State. INTRODUCTION 0 aquaculture; Zeolites are a diverse ‘supergroup’ of minerals, all 0 pet litter; being crystalline hydrated aluminosilicates of the 0 mordenite for removal of organochlorides from alkali and alkaline earth metals, particularly Ca, industrial effluent; and Na and K. They less commonly contain Ba, Li, Cs, Sr and Mg. Some 94 species are known, some of the 0 phillipsite to remove Cs and Sr from radioactive more important including clinoptilolite, chabazite, materials. mordenite, phillipsite, laumontite, stilbite, heulandite, analcime, natrolite and thomsonite. Natural zeolites may require some chemical They are all characterised by a 3D aluminosilicate modification prior to use. framework but have variable polyhedral groups and, importantly, relatively large channels and ECONOMIC FACTORS cavities between these polyhedra. These cavities Natural zeolite deposits may be economic, and channels can contain cations (e.g. metal ions), especially if the beds are several metres thick and water and other molecules, and give the zeolites relatively massive (i.e. >70% zeolites). The some of their most important properties, in regards thickness of mineable zeolite deposits can range up to their use as molecular sieves, catalysts, ion to several tens of metres, whilst the thickness of the exchange materials, etc. strata containing the zeolitic tuffs commonly ranges from 100’s to 1000’s of metres. Areal extent is USES commonly 100’s to 1000’s of square kilometres The zeolites have some unusual and important (Green River Basin, USA: Hay and Sheppard, characteristics, including capacity for ion-exchange 1977). The economics of mining are affected by the and molecular sieving which make many varieties thickness of overburden, and the distance to of considerable economic significance. Uses include transport links and processing plants. adsorption (e.g. removal of ammonia, heavy metals, The hardness and attrition resistance of zeolitic tuff radio isotopes, etc.), purification (particularly waste (mostly affected by the abundance of opal, water, sewage, hydrocarbons, air and gases), cristobalite, tridymite and quartz) are important in drying, kidney dialysis, hydrogen production (from processing and end use. The crystal size of the water), detergent production, animal feeds, zeolite (usually fine grained) can affect the fertilisers, aquaculture, hydrocarbon conversion adsorption of gases and the extent and rapidity of (e.g. conversion of methane to petroleum), cation exchange. The Si/Al ratio and exchangeable isomerisation, redox reactions, hydrogenation and cation ratios of the zeolites affect certain uses. dehydro- genation, organic catalysis (e.g. Cation exchange capacity and adsorption capacity shape-selective reforming), solar energy storage, for various gases are important. Colour (due to iron and many more (Mumpton, 1977; Clifton, 1987). staining) and the abundance of non-zeolitic Synthetic zeolites are very important in many of minerals may limit some uses. these applications, especially where high purity is required (particularly the chemical, oil, detergent GEOLOGICAL OCCURRENCES and other manufacturing industries). Natural Zeolite deposits may occur in: zeolites are, however, used in many applications (Rustamov et al., 1988; Clifton, 1987), for example: 1. saline, alkaline lakes; 0 clinoptilolite to remove NH4+ in tertiary sewage 2. saline, alkaline soils; treatment; 3. tuffaceous sea-floor sediments; 0 mine waste management; 4. open hydrological systems; and 0 agriculture (soil conditioner, fertiliser carriers and in animal feeds); 5. hydrothermal veins and zones. Tasmanian Geological Survey Record 1997/07 2 The major known economic deposits in the United economic significance, although submarine States are of types 1, 2 and 4 (Clifton, 1987). hydrothermal activity may be responsible for some of the zeolite deposits in marine sediments (Clifton, Saline, alkaline deposits form in closed hydrological 1987). systems in arid to semi-arid environments and contain some of the purest zeolite deposits (>90%, Zeolites may also occur in several other situations, Hay, 1977; Clifton, 1987; Surdam, 1977). Saline including as a primary magmatic mineral (analcime lakes forming in closed basins may have a pH of up in some basalts; Iijima, 1980), during burial to 9.5, promoting dissolution of aluminosilicates diagenesis (e.g. the Green Tuff sequence, Japan; (Hay, 1977). Deposits in the USA formed mostly Iijima, 1980), in contact metamorphic zones (Utada, from rhyolitic tuffs, but a wide variety of materials 1991), and in sediments in calderas (Utada, 1991) (including clays and quartz) may be altered to and impact craters (Iijima, 1980). With the zeolites under these conditions (Hay, 1978). exception of caldera deposits, these mineralisation Analcime, clinoptilolite, phillipsite, erionite, styles generally do not appear to be of any great chabazite and mordenite occur in these lakes. economic significance (Utada, 1991). Deposits in alkaline soils are related to the above Host rock types include igneous, metamorphic and style, but are limited by depth of the water table, sedimentary rocks, and vary from monomineralic, and are commonly analcime rich (Clifton, 1987; wholly zeolite-bearing lithologies to rocks with Surdam, 1977). They can contain up to 40% zeolites. occasional zeolitic geodes, veins or inclusions. Igneous hosts include volcanic ashes, lavas and Zeolites are very widespread in marine sediments tuffs (having a broad compositional range, (Iijima, 1978; Iijima and Utada, 1966; Lisitzina and including rhyolite, dacite, trachyte, phonolite, and Butuzova, 1982) and form by the alteration of basalt to basanite) and less commonly various tephra under low temperatures and moderate pH hypabyssal and plutonic rocks. The silicic tuffs were (~7–8, Clifton, 1987). Clinoptilolite is usually commonly deposited as non-welded permeable ash dominant in areas of rapid sedimentation, siliceous flows. Sedimentary host rock types include tephra and older sediments, while phillipsite fluviatile mudstone, siltstone, sandstone, commonly dominates in areas of slower conglomerate and diatomite. Metamorphic hosts sedimentation, basaltic tephra and younger (for hydrothermal deposits) are rarer, but include sediments (Hay, 1977). Phillipsite may alter to hornfels, amphibolite, schist and gneiss. clinoptilolite (Clifton, 1987). Associated zeolites include analcime, chabazite, erionite, laumontite, Zeolites form stratabound, stratiform or gmelinite, natrolite and thomsonite (Iijima and lens-shaped, zoned, massive, fine-grained deposits Utada, 1966). Deposits may contain up to 80% that may be cross-cutting to the bedding. They are zeolites. similar to bedded diatomite and bentonite. Most deposits are non-marine (fluviatile and lacustrine),