Quartz

Info: Quartz is one of the most common minerals on Earth. Quartz have many varieties, which are usually divided in two groups - typical for the first group is that the minerals in it are made by big crystals, for the second - that the minerals in it are made by tiny crystals of quartz. Members of the first group, made by makrocrystals - colourless transparent crystal, which when coloured to different colours made the purple amethyst, the brown to smoky smoky quartz, black morion, yellow citrine, blue quartz, or the pink coloured rose quartz. Aventurine is quartz with inclusions of little crystals of slida, the blue quartz gets its colour from the little needels of rutil, the green praseme gets its colour by little needels of amfibol. The second group contains the minerals chalcedony, jasper, to chalcedony can be attached his varieties carnelian, agate and onyx.

How to recognize: When breaking quartz in the dark it emits little sparkles. When heated to 200 C, it lights in yellow or blue colour. This quality is known as thermiluminiscence.

Found: Big quartz crystals were found in Italy, Swizerland, Madagascar, in the Alps, in the location of polar Urall (Russia).