Aventurine is a translucent to opaque variety of micro crystalline quartz. It contains small inclusions of shiny minerals which give the stone a sparkling effect known as aventurescence. Aventurine commonly ranges from light to dark-green in color. The color is caused by trace elements of fuchsite in colorless quartz. Fuchsite is a chromium rich variety of muscovite. Aventurine is often so heavily included with fuchsite, that it may be defined as a rock rather than a mineral. Aventurine is still classified as quartz by most geologists, who consider the fuchsite to be an inclusion within the quartz.
Aventurine's natural effect of 'aventurescence' ranges from weak to intense. The level of intensity depends on the quantity and size of the metallic inclusions. The color of Aventurine varies depending on which inclusions are present. Most Aventurine quartz appears almost banded with lighter and darker color layers. Aventurine has a grainy texture in its rough state, but when polished it has an attractive, soft and dull vitreous luster. Aventurine quartz is sometimes confused with Aventurine feldspar. Feldspar coloring is orange to red and it is more transparent, which makes it easily identifiable. The Aventurine feldspar variety is referred to as "Sunstone" while the Aventurine quartz variety is referred to simply as "Aventurine". Deposits are found in Brazil, India, Austria, Russia, and Tanzania.
It is interesting that the name for the stone is derived from an accident. Sometime during the 18th century, Venetian glass workers were preparing molten glass when copper filings accidentally fell into the batch producing a glass with sparkles. The name Aventurine comes from the Italian "a ventura," which means “by chance". Although it was known first, goldstone is now a common imitation of Aventurine and Sunstone.
Aventurine Display with Stand from Brazil
Aventurine with Display Stand from Brazil
From our Personal Collection comes this Old Stock specimen of Green Aventurine from Brazil
This specimen weighs 24.3 oz or 1.51 lbs (688g) and measures 4.2 x 3.4 x 1.9 inches (10.8 x 8.6 x 4.8cm) and stands on a 1" (2.6cm) tall wooden base