Reference work entry
Rock crystals are transparent quartz crystals with the composition SiO 2. Based on the characteristics and industrial usage, they can be categorized as piezoelectric rock crystals, optical rock crystals, smelting rock crystals and craft rock crystals. Craft crystals include all types of coloured quartz that can be used as handicraft materials. Rock crystals generally form in hydrothermal geodes (Fig. 16). As a gem, a rock crystal is a quartz crystal with high transparency and a perfect crystal shape. Rock crystals belong to the large quartz family and have a phanero-crystalline texture. Its main component is silica, and it may contain trace impurities of iron, manganese, magnesium, aluminium and titanium. Based on its colour, inclusions and nature, rock crystals can be categorised as amethyst, yellow quartz, smoky quartz, rose quartz, black crystals, hair quartz, agate, starlight crystals, cat’s eye quartz and sand crystals. Rock crystals are mainly found in quartz veins and cavities...
© Springer Nature Singapore Pte Ltd. 2020