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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 ...
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.
In cross-polarized light on the left, plane-polarized light on the right. Dark mica from eastern Ontario. Micas (/ ˈ m aɪ k ə z / MY-kəz) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as perfect ...
Optical properties of common minerals Name Crystal system Indicatrix Optical sign Birefringence Color in plain polars Anorthite: Triclinic: Biaxial (-) 0.013
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]
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.
The following tests are some examples of those that are used on hand specimens, or on field samples, or on thin sections with the aid of a polarizing microscope. Color; Color of the mineral. Color alone is not diagnostic. For example quartz can be almost any color, depending on minor impurities and microstructure. Streak
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.