nitric acid 2.5 in cubes tastes of salt halite 2 soluble in water, sweetish taste borax 2 1 perfect cleavage, and two imperfect gypsum cleaves at 66 with each other White or with faint tinges of color due to impurities, such as pink, bluish, etc. 7 hexagonal prisms quartz 7 non-crystalline chalcedony 7 or 4.5 cubes with beveled edges boracite 6 non-crystalline, pearly luster opal 6 cleavage in 3 directions, good in 2 feldspar and imperfect in the other 5.5 short eight-sided prisms pyroxene 5.5 long six-sided prisms amphibole 5.5 trapezohedrons analcite 5.5 tufts of needle-like crystals natrolite 5.5 sheaf-like bundles of crystals stilbite 5.5 rhombohedrons willemite 5 effervesces in acid smithsonite 5 becomes jelly-like in acid calamine 4.5 & 7 cubes with beveled edges boracite 4.5 monoclinic prisms colemanite 4 effervesces in acid, porcelainous magnesite 3.5-4 effervesces in acid, heavy, red color strontianite in flame 3.5 effervesces in acid, heavy, green witherite color in flame 3.5 effervesces in warm acid, rhomboidal dolomite cleavage 3.5 effervesces in acid, cleavage in one aragonite direction only 3.5 effervesces in acid, heavy, does not cerrusite color flame 3-3.5 no effervescence, cleavage in three anhydrite directions at right angles 3 effervesces in acid, rhomboidal calcite cleavage 3 tabular crystals, heavy, green color barite in flame 2-3 cleaves in thin elastic sheets mica 2.5 cleaves in cubes cryolite 2.5 cubes, soluble in water, salty taste halite 2 1 perfect cleavage, and 2 less perfect gypsum ones 2 cleaves in thin non-elastic sheets chlorite 2 soluble in water, tastes sweet borax 1 greasy feel talc Green 9 hexagonal prisms oriental