Sunday, April 21, 2013

Unusual Artifacts: The Townshend Cryptocrystalline Quartz, 1825

Golden Chalcedony Ring
The Townshend Collection at
The Victoria & Albert Museum

This nifty gem is cryptocrystalline quartz. This natural phenomenon occurs when quartz forms as a mass of microscopically small crystals. It’s also known as “microcrystalline quartz,” but I like cryptocrystalline better since it sounds spoooooooooooky.

This family of quartz includes many different gemstones such as chalcedony, agate, carnelian, jasper and sard. The colors of the stones vary slightly depending on the occurrence of different impurities such as iron, manganese and chrome.

This ring is one of the 154 gems bequeathed to the V&A by the Reverend Chauncey Hare Townshend. Like the others in the collection it was mounted in a gold setting for display purposes only. The Gothic-style gold setting dates to about 1825. So, what exactly is this stone? Well, guess what. It’s a rare example of chalcedony that isn’t the typical blue-gray color that we think of. Oddly enough, just the other day, I was having a conversation with my father about chalcedony and if it was possible for it to be any other color. I declared that I didn’t think it possible. But, I wasn’t sure, so I went digging for answers and this is the result. If, during formation, iron manganese or chrome in peculiar amounts is introduced to a cryptocrystalline gem, the color can be altered. This is a very, very rare event. But, it can happen. The result, in this case, from an introduction of iron is a chalcedony with a golden hue.

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