Most gemstone names are unambiguous, but aventurine is an exception. The name is used both for aventurine feldspar and aventurine quartz. The aventurine feldspar is now commonly sold under the name sunstone, leaving the name aventurine to be used mainly for the quartz variety.
The reason why both of these gems were labelled as aventurine is due to their resemblance to a type of Italian glass known as aventurine or goldstone. The name aventurine comes from the Italian a ventura, meaning "by chance," since it was thought that the unusual Italian glass was discovered by accident. In fact aventurine glass is credited to an Italian family of glassmakers by the name of Miotti. They created this special iridescent glass in the mid 17th century and it became quite famous. Their process for creating the glass remained a closely guarded secret for many years, and for a long time the Miotti family had the exclusive rights to produce it.
Eventually the word got out that aventurine glass was created by combining glass with copper or copper salts. When the glass melted and cooled, these mineral deposits would create a gold-flecked and shiny appearance on the glass. Though the glass was clear, the added minerals could create various colors such as green and blue, though the most common color is a rich reddish brown.
Aventurine quartz is sometimes classified as a rock since it contains more than one type of mineral. It is largely quartz, but also contains fuchsite (a type of mica) or hematite. The aventurine containing fuchsite is a medium to dark green with a silvery green or blue sheen. Aventurine with hematite is typically red-brown or gold-brown.
Fuchsite, the source of the green color in green aventurine, is a type of mica or muscovite containing chromium. It has a perfect basal cleavage yielding remarkably thin sheets that are often quite flexible. It is curious that the name muscovite also come from a kind of glass, Muscovy-glass, a name formerly used for the mineral because of its use in Russia for windows.
Aventurine quartz is found in Brazil, India, Austria, Russia and Tanzania. Aventurine is usually used for ornamental objects and cabochons, including beads and carvings.
- First Published: March-13-2009
- Last Updated: June-30-2014
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