Quartz and Epidote

Quartz [SiO₂] and Epidote [Ca₂Al₂Fe³⁺(SiO₄)(Si₂O₇)O(OH)] Sample of large, colourless to pale pink, translucent quartz [SiO₂] crystals associated with dark green epidote [Ca₂Al₂Fe³⁺(SiO₄)(Si₂O₇)O(OH)]. The quartz occurs as broad, euhedral prismatic crystals with well-developed rhombohedral terminations and vitreous lustre. Some crystals display internal cloudiness, inclusions, and locally developed pink to reddish colouration. Dark green to greenish-black epidote occurs between and upon the quartz crystals as subhedral to locally euhedral, tabular to short-prismatic crystals. The epidote displays vitreous lustre and contrasts strongly with the pale quartz. The specimen is identified as originating from a pegmatite, a very coarse-grained igneous rock commonly characterized by large crystals produced during the late stages of magma crystallization. Quartz has a Mohs hardness of 7 and no cleavage. Epidote has a Mohs hardness of approximately 6–7 and one direction of perfect cleavage.