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For example, some sources have assigned a Mohs hardness of 6 or 7 to granite but it is a rock made of several minerals, each with its own Mohs hardness (e.g. topaz-rich granite contains: topaz — Mohs 8, quartz — Mohs 7, orthoclase — Mohs 6, plagioclase — Mohs 6–6.5, mica — Mohs 2–4).
Granite containing potassium feldspar, plagioclase feldspar, quartz, biotite, and/or amphibole. Granite is nearly always massive (lacking any internal structures), hard (falling between 6 and 7 on the Mohs hardness scale) [specify], and tough. These properties have made granite a widespread construction stone throughout human history.
Mohs scale of mineral hardness; Mohs hardness of materials (data page) Vickers hardness test; Brinell scale This page was last edited on ...
Mohs scale hardness: 6 to 6.5: Luster: Vitreous: ... The Mohs hardness is 6 to 6.5 and the specific gravity is 2.64 to ... and calcite in veins in granite at Arendal ...
"Imperial Porphyry" from the Red Sea Mountains of Egypt A waterworn cobble of porphyry Rhyolite porphyry from Colorado; scale bar in lower left is 1 cm (0.39 in). Porphyry (/ ˈ p ɔːr f ə r i / POR-fə-ree) is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate-rich, generally aphanitic matrix or groundmass.
The Mohs scale of mineral hardness; The Vickers hardness test; The Brinell scale; The Janka hardness test; The Rockwell scale; The Durometer scale; The Barcol scale;
Mohs scale hardness: 6–7: Luster: Vitreous to resinous: Streak: Greyish white: ... It was first found in the granite of east Greenland and described by Thomas Allan ...
Mohs scale hardness: 4.5–5 parallel to one axis 6.5–7 perpendicular to that axis: ... Kyanite is also occasionally found in granite and pegmatites [9] [11] ...