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A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than 1 cm (0.4 in) and sometimes greater than 1 meter (3 ft). Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic composition to granite.
Spodumene occurs in lithium-rich granite pegmatites and aplites. Associated minerals include: quartz, albite, petalite, eucryptite, lepidolite and beryl. [3] Transparent material has long been used as a gemstone with varieties kunzite and hiddenite noted for their strong pleochroism.
In archaeology, lithic analysis is the analysis of stone tools and other chipped stone artifacts using basic scientific techniques. At its most basic level, lithic analyses involve an analysis of the artifact's morphology, the measurement of various physical attributes, and examining other visible features (such as noting the presence or absence of cortex, for example).
‘This time we found not just more carvings but the sculpture of a human face cut into the rock’
It occurs in lithium-bearing pegmatites with spodumene, lepidolite, and tourmaline. Petalite is an important ore of lithium, and is converted to spodumene and quartz by heating to ~500 °C and under 3 kbar of pressure in the presence of a dense hydrous alkali borosilicate fluid with a minor carbonate component. [ 8 ]
Greisen is a highly altered granitic rock or pegmatite, usually composed predominantly of quartz and micas (mostly muscovite). Greisen is formed by self-generated alteration of a granite and is a class of moderate- to high-temperature magmatic-hydrothermal alteration related to the late-stage release of volatiles dissolved in a magma during the ...
Fossil footprints show humans in North America more than 21,000 years ago, the earliest firm evidence for humans in the Americas and show people must have arrived here before the last Ice Age.
Plus, symptoms and expert tips to help identify and treat insect bites. ... When ants bite humans, it grabs the skin and also sprays a compound called formic acid, Frye explains. Ant bites tend to ...