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Streak plates with pyrite (left) and rhodochrosite (right). The streak of a mineral is the color of the powder produced when it is dragged across an unweathered surface. Unlike the apparent color of a mineral, which for most minerals can vary considerably, the trail of finely ground powder generally has a more consistent characteristic color, and is thus an important diagnostic tool in mineral ...
Peridot can be found in mafic and ultramafic rocks occurring in lava and peridotite xenoliths of the mantle. The gem occurs in silica-deficient rocks such as volcanic basalt and pallasitic meteorites. Along with diamonds, peridot is one of only two gems observed to be formed not in Earth's crust, but in the molten rock of the upper mantle. [1]
Mica is common in igneous and metamorphic rock and is occasionally found as small flakes in sedimentary rock. [6] It is particularly prominent in many granites , pegmatites , and schists , [ 7 ] and "books" (large individual crystals) of mica several feet across have been found in some pegmatites.
Malachite is a copper carbonate hydroxide mineral, with the formula Cu 2 CO 3 (OH) 2.This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fractures and deep, underground spaces, where the water table and hydrothermal fluids provide the means for chemical precipitation.
Siderite is commonly found in hydrothermal veins, and is associated with barite, fluorite, galena, and others. It is also a common diagenetic mineral in shales and sandstones , where it sometimes forms concretions , which can encase three-dimensionally preserved fossils . [ 6 ]
Lepidolite is found naturally in a variety of colors, mainly pink, purple, and red, but also gray and, rarely, yellow and colorless. Because lepidolite is a lithium-bearing mica, it is often wrongly assumed that lithium is what causes the pink hues that are so characteristic of this mineral.
It is the state rock of Missouri. The name is a portmanteau, formed from Mo (Missouri), zark , and ite (meaning rock). [1] Mozarkite consists essentially of silica (quartz - SiO 2) with varying amounts of chalcedony. It has won distinction as a particular form or variety of chert because of its unique variation of colors and its ability to take ...
Kaolinite (/ ˈ k eɪ. ə l ə ˌ n aɪ t,-l ɪ-/ KAY-ə-lə-nyte, -lih-; also called kaolin) [5] [6] [7] is a clay mineral, with the chemical composition Al 2 Si 2 O 5 4.It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO 4) linked through oxygen atoms to one octahedral sheet of alumina (AlO 6).