Schorl and Rubellite

Two samples of Tourmaline. Rubellite (pink) is thin, subhedral prismatic crystals with the rounded triangular cross-section visible. Schorl (black) is also thin subhedral prismatic crystals with visible striations along the length of the faces and a vitreous lustre. Average size of Rubellite crystal is: 1.5 cm x 0.2 cm x 0.1 cm. Average size of Schorl crystal: 2.0 cm x 0.3 cm x 0.2 cm. Tourmaline (Na(Mg,Fe)3Al6(BO3)3(Si6O18)(OH,F)4) can be black (Schorl), blue (Indicolite), pink and red (Rubellite), brown (Dravite), green, white (rare) or multicoloured. Lustre is vitreous and streak is white. Hardness is 7 to 7 1/2. Tourmaline is usually found as long or short prismatic crystals with striations along the length of the faces and has a rounded triangular cross-section. Tourmaline can also be radiating, columnar or compact in forms.