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List of rocks on Mars – Alphabetical list of named rocks and meteorites found on Mars; Rock cycle – Transitional concept of geologic time; List of rock formations: for a list of unusual or culturally significant rock outcrops; Leaverite – Rock in the field that looks interesting but is actually not
In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, ...
Leaders of states in the U.S. which have significant mineral deposits often create a state mineral, rock, stone or gemstone to promote interest in their natural resources, history, tourism, etc. Not every state has an official state mineral, rock, stone and/or gemstone, however.
Phaneritic (phaner = visible) textures are typical of intrusive igneous rocks, these rocks crystallized slowly below Earth's surface. As magma cools slowly the minerals have time to grow and form large crystals. The minerals in a phaneritic igneous rock are sufficiently large to see each individual crystal with the naked eye.
Anorthosite Moon rock collected by Apollo 16 astronauts. It is approximately 3.9 billion years old and is the largest Moon rock brought from the Moon. Black Rock: Tooele County, Utah, United States: Large rock on the shoreline of Great Salt Lake. Black Stone: Kaaba, Great Mosque, Mecca, Saudi Arabia: A highly respected Islamic stone set in the ...
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.
In structural geology, ultramylonite is a kind of mylonite defined by modal percentage of matrix grains [clarify] more than 90%. [4] Ultramylonite is often hard, dark, cherty to flinty in appearance and sometimes resemble pseudotachylite and obsidian. In reverse, ultramylonite-like rocks are sometimes "deformed pseudotachylyte". [5] [6] [7] [8]
Rock sample of ignimbrite, collected at the foot of Mount Guna in Ethiopia. Welding is a common form of ignimbrite alteration. There are two types of welding, primary and secondary. If the density current is sufficiently hot the particles will agglutinate and weld at the surface of sedimentation to form a viscous fluid; this is primary welding ...