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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 ...
The streak of a mineral is independent of trace elements [75] or any weathering surface. [79] A common example of this property is illustrated with hematite , which is coloured black, silver or red in hand sample, but has a cherry-red [ 75 ] to reddish-brown streak; [ 79 ] [ 7 ] or with chalcopyrite , which is brassy golden in colour and leaves ...
The streak is purplish-red, thus differing markedly from the scarlet streak of proustite and affording a ready means of distinguishing the two minerals. The Mohs hardness is 2.75, and the specific gravity 5.85. The refractive indices (nω = 3.084 nε = 2.881) and birefringence (δ = 0.203) are very high.
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.
Rhodochrosite is a manganese carbonate mineral with chemical composition MnCO 3. In its pure form (rare), it is typically a rose-red colour, [5] but it can also be shades of pink to pale brown. It streaks white, [6] and its Mohs hardness varies between 3.5 and 4.5. Its specific gravity is between 3.45 and 3.6. [7]
The mineral is used in cosmetics and food [9] to add "shimmer" or "frost". Properties and structure ... Streak: White, colorless: Specific gravity: 2.8–3.0 ...
Chalcopyrite is an exception to most copper bearing minerals. In contrast to the majority of copper minerals which can be leached at atmospheric conditions, such as through heap leaching, chalcopyrite is a refractory mineral that requires elevated temperatures as well as oxidizing conditions to release its copper into solution. [25]
Goethite (/ ˈ ɡ ɜːr t aɪ t /, [6] [7] US also / ˈ ɡ oʊ θ aɪ t / [8] [9]) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the α-polymorph. It is found in soil and other low-temperature environments such as sediment.