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2. Patuxent River stone - Wikipedia

   en.wikipedia.org/wiki/Patuxent_River_Stone

   Patuxent River stone. The Patuxent River stone is the state gem (a form of agate) of the U.S. state of Maryland. Since it is found in red and orange this stone could also be referred to as carnelian. [1] It is found only in Maryland, and its colors reflect the Maryland state flag. The Patuxent River stone became the state gem effective October ...

3. Greywacke - Wikipedia

   en.wikipedia.org/wiki/Greywacke

   Greywacke or graywacke (German grauwacke, signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness (6–7 on Mohs scale), dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or sand-size lithic fragments set in a compact, clay -fine matrix.

4. Quartz - Wikipedia

   en.wikipedia.org/wiki/Quartz

   Quartz. Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2. Quartz is, therefore, classified structurally as a framework silicate mineral ...

5. Prasiolite - Wikipedia

   en.wikipedia.org/wiki/Prasiolite

   Prasiolite. Prasiolite (also known as green quartz, green amethyst or vermarine) is a green variety of quartz. Since 1950, almost all natural prasiolite has come from a small Brazilian mine, [citation needed] but it has also been mined in the Lower Silesia region of Poland. Naturally occurring prasiolite has also been found in the Thunder Bay ...

6. Baraboo Quartzite - Wikipedia

   en.wikipedia.org/wiki/Baraboo_Quartzite

   Baraboo Quartzite is a Precambrian geological formation [ 1 ] of quartzite, found in the region of Baraboo, Wisconsin. While pure quartzite is usually white or gray, Baraboo Quartzite is typically dark purple to maroon in color, due to the presence of iron (hematite) and other impurities. [ 2 ] Baraboo Quartzite may display strata created by ...

7. Jasper - Wikipedia

   en.wikipedia.org/wiki/Jasper

   Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, [1][2] is an opaque, [3] impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron (III) inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as ...

8. Aventurine - Wikipedia

   en.wikipedia.org/wiki/Aventurine

   Aventurine. Aventurine is used for a number of applications, including landscape stone, building stone, aquaria, monuments, and jewelry. Aventurine is a form of quartzite, characterised by its translucency and the presence of platy mineral inclusions that give it a shimmering or glistening effect termed aventurescence.

9. Herkimer diamond - Wikipedia

   en.wikipedia.org/wiki/Herkimer_diamond

   Herkimer diamonds are double-terminated quartz crystals discovered within exposed outcrops of dolomite in and around Herkimer County, New York, and the Mohawk River Valley in the US. [1][2] They are not diamonds; the "diamond" in their name is due to both their clarity and well formed faces. Because the first discovery sites were in the village ...