Description
Aventurine is a green to reddish-brown variety of the mineral quartz. This gemstone usually occurs in green and cut varieties. Aventurine has a hardness of 7 and is found in Russia, the Urals, and China, among other places. Like many other varieties of quartz (such as amethyst and rose quartz), aventurine is cut for jewelry use. The chemical composition of aventurine is SiO2 + KAl2(OH,F)2 / AlSi3O10 + Cr. The ancient Greeks sewed aventurine into warriors' clothing to maintain their courage, ambition, and optimism.
Hematite (from Greek: αιμία, haima, blood) is a mineral composed primarily of ferric oxide crystals (iron(III) oxide, Fe2O3), one of the iron oxides. It occurs alongside other varieties such as red bloodstone and grayish-black to black iron luster and micaceous iron. The mineral has a hardness of between 5 and 6. The so-called streak, or streak color, the color the mineral imparts when rubbed over an unglazed porcelain dish, is usually a characteristic blood red—from which the mineral derives its name. The mineral may contain traces of magnesium, manganese, and titanium. Hematite occurs both as a gangue mineral and in sedimentary layers. It is often the cause of the red coloration of many rocks. Other iron ores such as magnetite, limonite, and iron spar often occur alongside hematite.
