CALCITE - CaCO₃ / QUARTZ - SiO₂  This is a very nice specimen of a geode section that has calcite crystals covering quartz and quartz crystals. The quartz is coated in areas by chlorite that gives it a dark color.Not often found w/ Chlorite. This specimen is 12.5 cm (5") wide by 9 cm (3-1/2") deep by 5 cm (2") high .The quartz crystals have a faint amethyst tint. From Irai, Rio Grande do Sul, Minas Gerais, Brazil.