Thursday, 20 October 2011

Anyolite ~ ruby in zoisite

Anyolite is a good example of the complexity of identifying rocks, minerals and gems.  I'm a rank amateur in this respect.  From what I can gather it's to do with chemical composition and the structure of these compounds in addition to the appearance of the specimens themselves, which can include many grades and types.  For further reading about identifying these I provide this link to Wikipedia's Mineral article.

The specimen shown here was sold to me as ruby in zoisite, which seems straightforward as I can easily identify the ruby, but it's not that simple.  I looked up zoisite and found that it belongs to the epidote family, which I've already written about.  But what's this: an image of a transparent gem!  My sample is certainly not this!  I read on and found that what I have here is not the gem form but metamorphic rock, and when ruby occurs in combination with it it is termed anyolite!  The article then goes on to say that it commonly has a glassy lustre.  This is absent from my piece, but it does have a great deal of glinting goldish metallic flecks in it.  I wonder if this is what they mean or if these are flecks of pyrite or mica?

The back of the stone is full of these glinting flecks!  In the photographs these have come out as a whitish colour so I may re-photograph it sometime to show these better.

Later Note: I am now of the opinion that the green stone isn't zoisite but fuchsite, although I can't be certain. Fuchsite is described as 'chrominium rich muscovite' on the page linked to here.  Muscovite is the most common form of the mineral, mica, which would account for the metallic flecks. In the article linked to here on the Wire Sculpture site there is a photograph which shows ruby in both zoisite and fuchsite and they do look similar. I'll look into this further at some stage.

No comments: