Phlogopite and Olivine

Pegmatitic black Phlogopite prismatic crystals (3.0 cm in diameter) with an adamantine lustre entwined with granular Peridot (1.0 cm in length). Phlogopite (KMg3(AlSi3O10)(OH)2) can be yellowish, reddish brown, grey, green or colourless (rare) with a pearly or adamantine lustre. Streak is colourless and hardness is 2 to 3. Cleavage is perfect in one direction. Phlogopite is often found as well formed prismatic crystals that have a hexagonal outline but can also be found as plates or scales. Olivine ((Mg,Fe)2SiO4) can be yellowish green (Peridot), yellowish brown or reddish in colour. Lustre is vitreous and streak is colourless. Hardness is 6 1/2 to 7 and cleavage is indistinct in two direction at 90 degrees. Olivine is usually rounded grains or granular masses.