calcite

A very common form of calcium carbonate

Fluorite and Calcite on Sphalerite

A silver sphalerite matrix with some purple fluorite crystals and a yellow calcite crystal on it.

Photo by Anton Watzl

Here is some fluorite (purple) and calcite (yellow) on sphalerite (silver). No further comments, I just thought this was pretty.

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The Blarney Stone

I don’t know about you, but I’m still in the St. Patrick’s Day spirit. This is the Blarney Stone, the most well-known rock in Ireland. The Blarney Stone is embedded 90 feet high in a tower of Blarney Castle, in the village of Blarney near Cork, Ireland. Legend has it that if you kiss the stone you will receive the skills of eloquence, persuasion, and flattery: in other words, blarney. Climb to the top of the tower, sit with your back to the stone, then have someone hold your legs down while you lean backwards to kiss the stone.

The Blarney Stone itself is carboniferous limestone, also known as bluestone. Geologists at Glasgow University analyzed a sample of the stone and determined that it is “limestone, made of the mineral calcite, and containing recrystallised and slightly deformed fragments of fossil brachiopod shells and bryozoans – all of which are unique to the region where it is based” (www.theguardian.com/world/2014/mar/16/mystery-blarney-stone-heritage-solved) Some stories suggest that the Blarney Stone was from Scotland, but this research shows that it is native to Ireland and is about 330 million years old. Erin go bragh!