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2. Chert - Wikipedia

   en.wikipedia.org/wiki/Chert

   Chalcedony is a microfibrous quartz. [16] Agate is distinctly banded chalcedony with successive layers differing in color or value. [66] Onyx is a banded agate with layers in parallel lines, often black and white (sardonyx). [67] Magadi-type chert is a variety that forms from a sodium silicate precursor in highly alkaline lakes such as Lake ...

3. Gold mining in Alaska - Wikipedia

   en.wikipedia.org/wiki/Gold_mining_in_Alaska

   The Donlin Gold project, in the Kuskokwim Gold Belt, contains a Proven and Probable Reserve of 33.8 million ounces at a grade of 2.09 g/t (using a gold price of US$975/oz), within a Measured and Indicated Resource of 39 million ounces of gold at 2.03 g/t. [11]

4. Quartz - Wikipedia

   en.wikipedia.org/wiki/Quartz

   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 ...

5. Eclogite - Wikipedia

   en.wikipedia.org/wiki/Eclogite

   A few gold-white phengite patches can be seen at the top. A 23 millimetres (0.91 in) coin added for scale. A 23 millimetres (0.91 in) coin added for scale. Eclogite ( / ˈ ɛ k l ə dʒ aɪ t / ) is a metamorphic rock containing garnet ( almandine - pyrope ) hosted in a matrix of sodium -rich pyroxene ( omphacite ).

6. Flint - Wikipedia

   en.wikipedia.org/wiki/Flint

   A piece of flint 9–10 cm (3.5–3.9 in) long, weighing 171 grams. Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, [1][2] categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start fires.

7. Pegmatite - Wikipedia

   en.wikipedia.org/wiki/Pegmatite

   Pegmatite. 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.