Aventurine is a form ofquartzite, characterised by its translucency and the presence ofplatymineralinclusions that give it a shimmering or glistening effect termedaventurescence.
The most common color of aventurine is green, but it can also be orange, brown, yellow, blue, or grey. Chrome-bearingfuchsite (a variety ofmuscovitemica) is the classic inclusion and gives a silvery green or blue sheen. Oranges and browns are attributed tohematite orgoethite. Because aventurine is arock, its physical properties vary: itsspecific gravity may lie between 2.64–2.69 and itshardness is somewhat lower than single-crystal quartz at around 6.5.[citation needed]
Aventurine feldspar orsunstone can be confused with orange and red aventurine quartzite, although the former is generally of a higher transparency. Aventurine is often banded and an overabundance of fuchsite may render it opaque, in which case it may be mistaken formalachite at first glance.[citation needed]
The nameaventurine derives from theItalian "a ventura" meaning "by chance". This is an allusion to the lucky discovery ofaventurine glass orgoldstone at some point in the 18th century. One story is that this kind of glass was originally made accidentally at Murano by a workman, who let some copper filings fall into the molten "metal", whence the product was calledavventurino. From the Murano glass the name passed to the mineral, which displayed a rather similar appearance.[1] Although it was known first, goldstone is now a common imitation of aventurine and sunstone. Goldstone is distinguished visually from the latter two minerals by its coarse flecks ofcopper, dispersed within the glass in an unnaturally uniform manner. It is usually a golden brown, but may also be found in blue or green.[citation needed]
The majority of green and blue-green aventurine originates inIndia (particularly in the vicinity ofMysore andChennai) where it is employed by prolific artisans. Creamy white, gray and orange material is found inChile,Spain andRussia. Most material is carved into beads and figurines with only the finer examples fashioned intocabochons, later being set intojewelry.[citation needed]
One or more of the preceding sentences incorporates text from a publication now in thepublic domain: Chisholm, Hugh, ed. (1911). "Aventurine".Encyclopædia Britannica. Vol. 3 (11th ed.). Cambridge University Press. p. 54.
