Corundum Corundum is a crystalline form of aluminium oxide typically containing traces of iron, titanium, vanadium and chromium. It is a rock-forming mineral. It is also a naturally transparent material, but can have different colors depending on the presence of...
Chalcedony Chalcedony is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic. Varieties of...
Carnelian Carnelian is a brownish-red mineral commonly used as a semi-precious gemstone. Similar to carnelian is sard, which is generally harder and darker. Both carnelian and sard are varieties of the silica mineral chalcedony colored by impurities of iron oxide....
Agate Agates are characterized by multiple thin laminations of chalcedony that define distinct banding. many agates are found as amygdales in basalts and other volcanic rocks. Agates can be found in a wide spectrum of colours and can be found South Africa, Namibia,...
Vanadinite Vanadinite is easily identifiable by its perfect hexagonal crystals. The crystals are invariably a vibrant red but can be various shades from amber, to brown and red as well as brown and yellow. Vanadinite is found in South Africa, Namibia and Zimbabwe...
