Nephrite, Ca2(Mg, Fe)5Si8O22(OH)2, is one of two minerals more commonly known as what anciently treasured green gemstone, and once considered China's 'imperial gem'?
Nephrite Nephrite Nephrite is a variety of the calcium, magnesium, and iron-rich amphibole minerals tremolite or actinolite (aggregates of which also make up one form of asbestos). The chemical formula for nephrite is Ca(Mg, Fe)SiO(OH). It is one of two different mineral species called jade. The other mineral species known as jade is jadeite, which is a variety of pyroxene. While nephrite jade possesses mainly grays and greens (and occasionally yellows, browns or whites), jadeite jade, which is rarer, can also contain blacks, reds, pinks and violets. Nephrite jade is an ornamental stone used in carvings, beads, or cabochon cut gemstones.
Clinohumite Clinohumite Clinohumite is an uncommon member of the humite group, a magnesium silicate according to the chemical formula (Mg, Fe)(SiO)(F,OH). The formula can be thought of as four olivine (MgSiO), plus one brucite (Mg(OH)). Indeed, the mineral is essentially a hydrated olivine and occurs in altered ultramafic rocks and carbonatites. Most commonly found as tiny indistinct grains, large euhedral clinohumite crystals are sought by collectors and occasionally fashioned into bright, yellow-orange gemstones. Only two sources of gem-quality material are known: the Pamir Mountains of Tajikistan, and the Taymyr region of northern Siberia. It is one of two humite group minerals