Resource Sheet Rock forming minerals examples – Hardness Density Colour Streak Lustre Acid Test Mineral Mohs scale g cm3 vitreous, colourless, 2 white pearly or no reaction 2.3 gypsum white or grey earthy white to pale 2–2½ white vitreous no reaction 2.8–2.9 muscovite gree/yellow grey-black to bluish-black 2½ metalic no reaction 7.6 galena black to grey vitreous, colourless, tan, reacts 3 white pearly or 2.7 calcite white, or grey vigorously waxy white to tan or vitreous or reacts 3½–4 white 2.85 dolomite pinky grey pearly slowly colourless, vitreous to reacts 3½–4 white 2.95 aragonite white, or grey waxy vigorously colourless, green, purple, 4 white vitreous no reaction 3.2 fluorite blue, yellow, pink greenish-black 5–6 white vitreous no reaction 3.0–3.5 amphibole or dark-green medium-green, vitreous or 5–6 light-yellow to white no reaction 3.2–3.6 pyroxene earthy pale-bronze white to 6–6½ white vitreous no reaction 2.5–2.6 orthoclase salmon pink white to dark 6–6½ white vitreous no reaction 2.6–2.8 plagioclase grey pale-yellow to vitreous to 6½–7 olive-green to white no reaction 3.3–4.4 olivine sub-metallic dark brown 6–6½ brass-yellow black metalic no reaction 5.0 pyrite colourless, rose to purple, quartz 7 vitreous no reaction 2.65 – smoky-grey to (crystal) brown-yellow milky, grey to vitreous to Black, red, to quartz 7 waxy to no reaction 2.65 – brown-yellow, (massive) earthy green, blue,
Resource Sheet Rock forming minerals – examples Hardness Mohs scale Colour Streak Lustre Acid Test Density g cm3 Mineral 2 colourless, white or grey white vitreous, pearly or earthy no reaction 2.3 gypsum 2–2½ white to pale gree/yellow white vitreous no reaction 2.8–2.9 muscovite 2½ grey-black to black bluish-black to grey metalic no reaction 7.6 galena 3 colourless, tan, white, or grey white vitreous, pearly or waxy reacts vigorously 2.7 calcite 3½–4 white to tan or pinky grey white vitreous or pearly reacts slowly 2.85 dolomite 3½–4 colourless, white, or grey white vitreous to waxy reacts vigorously 2.95 aragonite 4 colourless, green, purple, blue, yellow, pink white vitreous no reaction 3.2 fluorite 5–6 greenish-black or dark-green white vitreous no reaction 3.0–3.5 amphibole 5–6 medium-green, light-yellow to pale-bronze white vitreous or earthy no reaction 3.2–3.6 pyroxene 6–6½ white to salmon pink white vitreous no reaction 2.5–2.6 orthoclase 6–6½ white to dark grey white vitreous no reaction 2.6–2.8 plagioclase 6½–7 pale-yellow to olive-green to dark brown white vitreous to sub-metallic no reaction 3.3–4.4 olivine 6–6½ brass-yellow black metalic no reaction 5.0 pyrite 7 colourless, rose to purple, smoky-grey to brown-yellow – vitreous no reaction 2.65 quartz (crystal) 7 milky, grey to Black, red, to brown-yellow, green, blue, – vitreous to waxy to earthy no reaction 2.65 quartz (massive)