What is Aventurescence?

Aventurescence Optical Reflectance

Aventurescence is a reflectance seen in certain minerals and gemstones.  Best known for being present in aventurine, it's described as a metallic glitter caused by minute plate-like mineral inclusions.

When present in abundance the inclusions can influence the colour of the stone.

As light reflects off inclusions a kind of spangled reflection can be seen.  This optical phenomenon is aventurescence.

As well as being present in aventurine aventurescence can also be seen in sunstone.  

In sunstone it's caused as light reflects off minute inclusions of copper.  Sunstone is also known as aventurine feldspar.

The word "aventurescence" is widely reported to have come from the Italian "a ventura" meaning "by chance".  This is said to have come about following the "chance discovery" by Italian monks of aventurine glass which is also known as goldstone.

Depending on the article you read, the occurrence is said to have taken place in the 13th, 17th, 18th or 19th century.  

We can find no factual evidence to support this event.  

The story claims Venetian glass making monks accidentally dropped a jar filled with specs of copper into a vat of molten glass. Once the mixture cooled and solidified it had a spangled or glittery appearance.

The material is said to have been named aventurine glass because it was discovered "by chance".

From factual historical documentation we know aventurine glass (goldstone) is believed to have been created by Italian physicist and astronomer Vincenzo Miotti.

The mineral aventurine which is also known as aventurine quartz is likely to have been named after aventurine glass.

Aventurine feldspar also known as sunstone may also have been named after this man-made material.  All three exhibit the optical phenomenon of aventurescence.