Emmelberg, Üdersdorf, Daun, Vulkaneifel, Rhineland-Palatinate, Germany

Al₂SiO₄(F,OH)₂

Crystal System: orthorhombic
Colour: colourless, white, pale blue, light green, yellow, yellowish brown or red
Lustre: vitreous
Habitus: crystals are relatively common, prismatic, with striations paralllel to the crystal elongation. Also in compact or massive aggregates.
Hardness: 8
Fracture: irregular/uneven, sub-conchoidal
Cleavage: perfect {001}
Density: 3.55 g/cm³
Origin and geological occurrence: topaz occurs in pegmatites, high-T quartz veins and alluvial deposits. Also found in cavities of granites and rhyolites.

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Smorf link

Samples:

9A.9 Topaz Rounded anhedral grains #neso soro silicates