Spodumene

Hiddenite is named after the American geologist Hidden. The coloration is caused by the admixture of chrome or iron. The most expensive natural color of this gemstone variety is medium green. Kunzite is named after the geologist Kunz, who first described it in 1902. The pink to violet coloration is due to the addition of manganese. All three varieties have a vitreous luster and so-called pleochroism, which means that they show different colors under different viewing angles. Stones that are not suitable for jewelry production or as collector's items are used for the extraction of lithium. Spodumene forms in pegmatites or granites either magmatically or by hydrothermal processes. While the magmatically formed stones are mostly opaque, the hydrothermal formation produces clear and high-quality stones. There are currently about 450 known sites worldwide, the most important sites are located in Afghanistan, Brazil, Madagascar, the US and Pakistan. The size of the stones found is usually between a few centimeters and several decimeters, but record sizes of several meters are also possible: crystals up to 14 meters long and weighing 66 tons were found in a mine in South Dakota. Spodumene is fired at temperatures around 150 degrees Celsius to improve the color, i.e. to intensify the green tone of hiddenite or the pink tone of kunzite. But firing at 300 degrees Celsius and more or prolonged, punctual exposure to ligh causes the stones to fade. Under UV radiation, some stones show a yellow-orange or pink fluorescence.