Rock Crystal, traditionally called Pure Quartz or clear quartz, is colorless and transparent or translucent, and has often been used for hardstone carvings, such as the Lothair Crystal. Common colored varieties include citrine, Rose Quartz, amethyst, smoky quartz , milky quartz, and others.
The most important distinction between types of quartz is that of macrocrystalline (individual crystals visible to the naked eye) and the microcrystalline or cryptocrystalline varieties (aggregates of crystals visible only under high magnification). The cryptocrystalline varieties are either translucent or opaque, while the transparent varieties tend to be macrocrystalline. Chalcedony is a cryptocrystalline form of sillica consisting of fine intergrowths of both quartz, and it's monoclinic polymorph moganite. Other opaque gemstone varieties of quartz, or mixed rocks including quartz, including contrasting bands or patterns of color, are agate, Carnelian or sard, onyx, heliotrope, and jasper .
- Rock Crystal is one of the materials Jack Blacksmith uses at Hellfire Forge.