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Ajoite in quartz from Messina District, South Africa (size: 16.9 x 3.7 x 3 cm.) Ajoite is named after its type locality , the New Cornelia Mine in the Ajo District of Pima County , Arizona . Type material is conserved at the National Museum of Natural History , Washington DC, US, reference number 113220.
Quartz is, therefore, classified structurally as a framework silicate mineral and compositionally as an oxide mineral. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. [10] Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation ...
The Central African Republic did not produce mineral fuels in 2006 and depended upon imports for its energy requirements. United Reef Ltd. of Canada obtained the rights to a petroleum exploration permit in the country through a "farm-in agreement" with Denver-based RSM Production Corp. in 2004. It was unable to continue with its exploration ...
First found in the United States, unakite has a worldwide distribution, having also been reported in South Africa, Sierra Leone, Brazil, China, India and Australia. Some material labeled unakite lacks the feldspar and is more properly called epidosite, and is also used as beads and cabochons.
PPC Ltd, a supplier of cement, lime (material) and related products in southern Africa. It has 11 cement factories and a lime manufacturing facility in six African countries including South Africa , Botswana , Democratic Republic of the Congo , Ethiopia , Rwanda and Zimbabwe .
Although the term jasper is now restricted to opaque quartz, the ancient iaspis was a stone of considerable translucency including nephrite. [2] The jasper of antiquity was in many cases distinctly green, for it is often compared to emerald and other green objects. Jasper is referred to in the Nibelungenlied as being clear and green.
A Klerksdorp sphere. It is 3 to 4 centimetres (1.2 to 1.6 in) in maximum diameter and 2.5 centimetres (0.98 in) in thickness. Klerksdorp spheres are small objects, often spherical to disc-shaped, that have been collected by miners and rockhounds from 3-billion-year-old pyrophyllite deposits mined by Wonderstone Ltd., near Ottosdal, South Africa.
The room-temperature form of quartz, α-quartz, undergoes a reversible change in crystal structure at 573 °C to form β-quartz.This phenomenon is called an inversion, and for the α to β quartz inversion is accompanied by a linear expansion of 0.45%.