D-Gemstone Guess What It Is (not Diamond)!

I will give some hints.  It can be bright green to emerald green, brown, colourless and black.  The favourite colour for jewellery is the emerald green.   The black variety shows a star.  Rhymes with pesticide.  The gemstone is …
Crystal of Diopside

Flickr photo by Fluor_doublet

Diopside!

The emerald green variety is called “chrome diopside” and it has chromium in it!  Is is a beautiful stone.  Why don’t we find it in more jewellery stores?  It is not very hard (not as hard as quartz), so it is best suited for earrings or pendants.

Chrome Diopside

Flickr photo by MetalRiot

The black variety shows asterism and is known as “black star diopside”.  This means that it shows a star that seems to move on the surface when you move the stone.  There are four rays that are not at right angles, the arms intersect at about 75 and 105 degrees (very difficult to photograph).  These stones are magnetic due to the iron inclusions causing the star.

Black Star Diopside

Flickr photo by James Picht

Diopside is of interest to diamond prospectors because diopside is an indicator mineral for diamond.  This means that if you find chrome-rich diopside (and pyrope garnet, picroilmenite, chromite, olivine and diamond) on the surface of the earth this may help the prospector find a diamond bearing kimberlite pipe.  Diopside is found at South Africa – Kimberley diamond mines, Burma, Pakistan, Siberia – Russia, Sri Lanka, Brazil, Austria, Canada, the Malagasy Republic and the USA.  This hand-size specimen of kimberlite below shows several chrome green diopsides and smaller wine-red pyrope garnets.  This piece of kimberlite is from the Cumberland Peninsula, Baffin Island, Nunavut, Canada.

Flickr photo by subarcticmike

Natural Resources Canada provides a cool animated video describing the creation of diamonds and finding kimberlite diamond pipes with indicator minerals including diopside! Click on the Indicator Mineral Train box at the end to see details and which gemstones are contained in the indicator mineral train.

So get outside and look for diopside – maybe you will find a kimberlite pipe containing diamonds!

Your Input (Join our poll or scroll down and leave a comment)

I plan to introduce different gemstones alphabetically.  I will start with “A” (Ammolite) and see where it leads me.  Leave a comment and let me know if you have a favourite gemstone that starts with the letter “E” (other than emerald).  Take the poll (Emerald is the most popular gemstone so far)!  Can you name a reference to a gemstone in a song, movie or book?

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About Jen McKercher

Jennifer McKercher teaches gemmology at the Canadian Gemmological Association. A passion for gemstones drives Jen to learn as much as she can about the wonders of gemstones and how they enhance our lives.

Posted on June 30, 2011, in Individual Gemstones and tagged , , , , , , , , , , , , . Bookmark the permalink. Leave a comment.

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