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Lithics Reference Libraries

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Chert
2005-05-26 11:30:45

Chert is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils. It varies greatly in color from white to black, but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements present in the rock, and both red and green are most often related to traces of iron (in its oxidized and reduced...

Quartz
2005-05-25 18:55:31

Quartz is the second most abundant mineral in the Earth's crust. It has a hexagonal crystal structure made of trigonal crystallized silica (silicon dioxide, SiO2), with a hardness of 7 on the Mohs scale. Density is 2.6 g/cm³. The typical shape is a six-sided prism that ends in six-sided pyramids, although these are often distorted, or so massive that only part of the shape is apparent from a...

Word of the Day
abactinal
  • Pertaining to the surface or end opposite to the mouth in a radiate animal.
The word 'abactinal' comes from a Greek root meaning 'ray' and a Latin prefix meaning 'away'.
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