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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 ...
Sheet mica is a versatile and durable material widely used in electrical and thermal insulation applications. It exhibits excellent electrical properties, heat resistance, and chemical stability. Technical grade sheet mica is used in electrical components, electronics, atomic force microscopy and as window sheets.
Polarite, is an opaque, yellow-white mineral with the chemical formula Pd, (Bi,Pb). Its crystals are orthorhombic pyramidal, but can only be seen through a microscope. It has a metallic luster and leaves a white streak. Polarite is rated 3.5 to 4 on the Mohs Scale. [3][4]
It can be transparent to opaque, has a vitreous to pearly luster, and a grey-white streak. When biotite crystals are found in large chunks, they are called "books" because they resemble books with pages of many sheets. The color of biotite is usually black and the mineral has a hardness of 2.5–3 on the Mohs scale of mineral hardness.
A generalization is that minerals with metallic or adamantine lustre tend to have higher specific gravities than those having a non-metallic to dull lustre. For example, hematite , Fe 2 O 3 , has a specific gravity of 5.26 [ 87 ] while galena , PbS, has a specific gravity of 7.2–7.6, [ 88 ] which is a result of their high iron and lead ...
Labradorite is an intermediate to calcic member of the plagioclase series. It has an anorthite percentage (%An) of between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573 and twinning is common.
Staurolite is a reddish brown to black, mostly opaque, nesosilicate mineral with a white streak. It crystallizes in the monoclinic crystal system, has a Mohs hardness of 7 to 7.5 and the chemical formula: Fe 2+2 Al 9 O 6 (SiO 4) 4 (O,OH) 2. Magnesium, zinc and manganese substitute in the iron site and trivalent iron can substitute for aluminium.
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).