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It crystallizes in the monoclinic system, usually as long prismatic crystals showing a diamond-shaped cross section, but also in fibrous, bladed, acicular, columnar, and radiating forms. Its Mohs hardness is 5.0–6.0, and its specific gravity is 3.0–3.4. Cleavage is perfect, two directions in the shape of a diamond; fracture is uneven ...
Wulfenite is a lead molybdate mineral with the formula Pb Mo O 4.It often occurs as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable.
Amethyst crystals – a purple quartz Apophyllite crystals sitting right beside a cluster of peachy bowtie stilbite Aquamarine variety of beryl with tourmaline on orthoclase Arsenopyrite from Hidalgo del Parral, Chihuahua, Mexico Aurichalcite needles spraying out within a protected pocket lined by bladed calcite crystals Austinite from the Ojuela Mine, Mapimí, Durango, Mexico Ametrine ...
Both natural and synthetic zincite crystals are significant for their early use as semiconductor crystal detectors in the early development of crystal radios before the advent of vacuum tubes. As an early radio detector it was used in conjunction with another mineral, galena , and this device was known as the cat's-whisker detector .
Moissanite (/ ˈ m ɔɪ s ə ˌ n aɪ t /) [5] is naturally occurring silicon carbide and its various crystalline polymorphs.It has the chemical formula SiC and is a rare mineral, discovered by the French chemist Henri Moissan in 1893.
Scotlandite occurs as chisel-shaped or bladed crystals elongated along the c-axis, with a tendency to form radiating clusters. Its crystals are characterized by the {100}, {010}, {011}, {021}, {031}, and {032}. faces. Scotlandite shows perfect cleavage along the {100} plane and a less good one along the {010} plane. The measured density is 6.37 ...
Well-developed crystals are found at many localities: Knappenwand, near the Großvenediger in the Untersulzbachthal in Salzburg, as magnificent, dark green crystals of long prismatic habit in cavities in epidote schist, with asbestos, adularia, calcite, and apatite; the Ala valley and Traversella in Piedmont; Arendal in Norway; Le Bourg-d ...
Most serpentines are opaque to translucent, light (specific gravity between 2.2 and 2.9), soft (hardness 2.5–4), infusible and susceptible to acids. [1] All are microcrystalline and massive in habit, never being found as single crystals. Lustre may be vitreous, silky or greasy. Colors range from white to grey, yellow to green, and brown to ...