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Aventurine is a form of quartz, characterised by its translucency and the presence of platy mineral inclusions that give a shimmering or glistening effect termed aventurescence.
The most common colour of aventurine is green, but it may also be orange, brown, yellow, blue or gray. The most rare colour of aventurine is red, and it has been found only in one location in the world, which is located in Northern Ontario, Canada (Eldee, Ontario) near the Quebec border not far West from Temiskaming, Quebec. This rare specimen comes from the McLarens Bay Mica Stone Quarry MICASTONE.com
Chrome-bearing fuchsite (a variety of muscovite mica) is the classic inclusion, and gives a silvery green or blue sheen. Oranges and browns are attributed to hematite or goethite. Because aventurine is a rock, its physical properties vary: its specific gravity may lie between 2.64-2.69 and its hardness is somewhat lower than single-crystal quartz at around 6.5.
Aventurine feldspar or sunstone 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 for malachite at first glance.
The name aventurine derives from the Italian "a ventura," meaning "by chance." This is an allusion to the chance discovery of aventurine glass or goldstone at some point in the 18th century. 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 platelets of copper, dispersed within the glass in an unnaturally uniform manner. It is usually a golden brown, but may be stained blue to create "bluestone."
The majority of green and blue-green aventurine originates in India (particularly in the vicinity of Mysore and Madras) where it is employed by prolific artisans. Creamy white, gray and orange material is found in Chile, Spain and Russia. Most material is carved into beads and figurines with only the finer examples fashioned into cabochons, later being set into jewellery.
Further to the McLaren's Bay Mica Stone quarries mentioned above: It was created approximately 3.4 billion years ago when the molten quartz and molten mica came together to create this unique rare semi-precious gemstone. What is more unique is there are 3 colours in this single quarry. It contains red, green, and black, and they all co-exist. This means you occaisionally find a rock with black on one side and green on the other, or green on one side and red on the other. The formation was created deep below the surface, but at some point about 2 billion years ago, the table was thrust upwards on one end which turned it vertically. Then several ice age periods with glaciers moving which polished the top. This makes for an environmentally friendly 100% surface mining without any digging.
Main markets for aventurine are landscape stone, building stone, aquaria, monuments, and jewellery.
See also
"Aventurine"