Monday, October 20, 2014

Topaz crystals from Brazil


Everybody has their pet crystals which are part of the family, like one's dog or cat. I don't have any animals in my flat so I make do with crystals, minerals and fossils. Let me introduce my three favourite topazes of which two were bought at a mineral dealer's shop in Belo Horizonte in Minas Gerais, Brazil.

(1) The largest crystal weighs 873 grams and is flawless and colourless. In the foto it appears to have some colour but this is due to some residual iron oxide coating. It sits on its perfect basal cleavage and measures 2 x 4 inches and height 3 inches. It has a frosted water-worn surface of the original tetragonal prism and pyramid faces, which are terminated by the brilliant basal cleavage planes. You can see through it like binoculars. Each morning I use it as a weight to exercise my arm muscles.

(2) The smaller euhedral topaz weighing 149 grams exhibits the tetragonal prisms, sets of domes and pyramids and the basal pinacoid. Its size is 2 x 1 inches and 2 inches tall. It sits on its basal cleavage plane. It is a nice specimen and is a "handler crystal".

(3) Not to be forgotten is my favourite "handler topaz". Size is about 1 1/2 inches and it is a flawless angular
specimen except where the two basal cleavages are present either side.

Well there you are. How do I know that these crystals are topaz? (and not quartz, say). The perfect cleavage present is a dead give away. Also I have measured the specific gravity which comes to about 3.55 (or grams/cc). How do you do this? Why not buy my eBook "Playing Around with Minerals and Gemstones" and find out. Cheers, Allano