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Rock n Gem Magazine Issue 40

Published Summer 2007

Looking back

Collecting Scottish Agates

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MOSS and PLUME AGATES

Continuing Barry’s passion for inclusions in anything, this issue it’s Agate.

Plume Agate
Another type of structure often seen is called a plume, here wispy examples can be found in either agates or cut quartz. Inclusions often look like smoke drifting over red flames, like burning stubble on a farm or the Indian Smoke-signals seen in classic westerns. The plumes themselves can comprise various colours and they often have a halo or corona surrounding them. When this structure is identified, it can be found adjacent to or even included with other manganese dendrites. The distinctive types often overlap, plume structures are also found in other material such as jasper.


Moss Agate
This agate type is also referred to as Mocha stone, they are the same type. Moss Agate is a delicate fluffy structure that is often found in agates; here you can imagine walking through an enchanted forest with soft delicate fronds of moss hanging from the branches of trees. Gem cutters will often give the various individual varieties descriptive names, like green moss agate or a yellow moss agate. Three-dimensional green fronds with a moss like structure, similar to dendrites often occur in a translucent or opaque Chalcedony such as the green tree moss agate. Moss Agates are also found in other bright colours, rather than the typical green moss structure we are used to, the background is often very colourful too. The colours are the result of trace amounts of a metallic element usually an Iron oxide.
Fine green fronds or stringers are often found in a translucent chalcedony envelope. Other Moss Agates can often be found in opaque tubes which when cut open or through, reveal the typical green centre in the tubes. A large variety of colourful moss agate types exist, as more and more varieties are discovered every year, this can be very confusing, as the subtle varieties do frequently overlap in the original material. Another moss like agate that is referred to as Mosquito Agate, seems to be a denser form of moss agate, the sample I have is from Botswana.

Cutting and polishing
Unfortunately for the jewellery makers, many varieties of moss inclusions look their best when backlit. When this occurs they are cut into smaller carefully crafted pieces, set with perhaps a reflective backing, or often no backing at all, making maximum use of any available light.
Barry Taylor

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