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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 ...
Optical properties of common minerals Name Crystal system Indicatrix Optical sign Birefringence Color in plain polars Anorthite: Triclinic: Biaxial (-) 0.013
Pyrargyrite is a sulfosalt mineral consisting of silver sulfantimonite, Ag 3 SbS 3. Known also as dark red silver ore, ruby blende, garnete blende or ruby silver, it is an important source of the metal. It is closely allied to, and isomorphous with, the corresponding sulfarsenide known as proustite or light red silver ore.
Streak can be used when properties between pyrrhotite and other sulfide minerals are similar. Pyrrhotite displays a dark grey to black streak. [15] Pyrite will display a greenish black to brownish black streak, [16] chalcopyrite will display a greenish black streak, [17] and pentlandite leaves a pale bronze-brown streak. [18]
Optical mineralogy is the study of minerals and rocks by measuring their optical properties. Most commonly, rock and mineral samples are prepared as thin sections or grain mounts for study in the laboratory with a petrographic microscope. Optical mineralogy is used to identify the mineralogical composition of geological materials in order to ...
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.
Mineralogy applies principles of chemistry, geology, physics and materials science to the study of minerals. Mineralogy [n 1] is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts.
Strontianite is colourless, white, gray, light yellow, green or brown, colourless in transmitted light. It may be longitudinally zoned. It is transparent to translucent, with a vitreous (glassy) lustre, resinous on broken surfaces, and a white streak. It is a biaxial(−) mineral.