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Metamorphic rocks
Published in W.S. MacKenzie, A.E. Adams, K.H. Brodie, Rocks and Minerals in Thin Section, 2017
W.S. MacKenzie, A.E. Adams, K.H. Brodie
At higher temperatures, metabasic blueschist facies rocks contain epidote in place of lawsonite. This rock (Figure 253 at lower magnification and Figure 254 & 255) contains high relief, euhedral pink garnet which is isotropic and hence black in crossed polars, subhedral, high relief epidote (elongate grains, abundant at the top of the field of view, often with darker cores which are likely to be a type of epidote rich in rare earth element, allanite) with bright interference colours, blue pleochroic glaucophane (variable colours due to different orientations), and colourless platey white mica (bright interference colours), and quartz with low relief and low interference colours. The small grains with very high relief are sphene, which has extreme pale interference colours in crossed polars. The schistosity is defined by the alignment of white mica, glaucophane and epidote.
Industrial minerals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Species piemontite and allanite, (Ca,Fe2)2 (R,Al,Fe3)3Si3O12OH; (R = rare elements), belong to the same isomorphous group with epidote and are described as manganese and cerium epidotes, respectively. Piemontite is commonly found as small, reddish black, mono-clinic crystals in manganese mines while allanite has the same general epidote formula and contain metals of the cerium group.
Mineralogy and origin of Carboniferous and Cretaceous kaolins from a number of localities in Egypt
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
The studied kaolin deposits contain wide varieties of accessory minerals, the coarser of which are quartz, feldspars, muscovite, and heavy minerals (zircon, rutile, magnetite, tourmaline and ilimenite). However, they usually contain micro-size, minerals such as anatase, brookite, limonite, lepedochrocite, rhodochroite, hematite, goethite, siderite, natrolite, allanite, organic matter, illite (hydromuscovite), smectite, chlorite and mixed-layer clays. Some of the studied samples contain gypsum, anhydrite, nepheline, amorphous and microcrystalline silica.
Geochemical characteristics and structural setting of lithium–caesium–tantalum pegmatites of the Dorchap Dyke Swarm, northeast Victoria, Australia
Published in Australian Journal of Earth Sciences, 2023
B. R. Hines, D. Turnbull, L. Ashworth, S. McKnight
The Anglers Rest Granite is an Early to Middle Devonian I-type granite, forming a large, northeast-trending pluton south of Glen Wills (Figure 2; Morand et al., 2005). The Anglers Rest Granite is a homogeneous, equigranular medium to coarse-grained leucocratic granite. It is composed of pink, medium- to coarse-grained equigranular biotite leucogranite with minor muscovite and hornblende locally present (Figure 4j). Accessory minerals include common allanite, rare sphene, apatite, zircon, magnetite and ilmenite. Three biotite K–Ar dates obtained from the Anglers Rest Granite indicate an age of 400 ± 16 Ma (Richards & Singleton, 1981).