Ireland

Rocks and specimens from Ireland

Emeralds

Emeralds are the most famous green gemstone. The word emerald is practically synonymous with the color green, and in fact, the name emerald comes from the Greek smaragdos which means “green gem.” Ireland’s nickname “The Emerald Isle” sadly does not refer to any emeralds found there but for the green scenery.

Emeralds are the green variety of the mineral beryl. The famed green color comes from chromium impurities. When beryl appears in other colors due to different impurities it is called aquamarine (blue), morganite (pink), bixbite/red beryl (red), or heliodor (yellow). Emerald rates 7.5-8.0 on the Mohs hardness scale, though it can be brittle. Emeralds are usually found in Colombia (South America) or Zambia (Africa) in granite pegmatites and metamorphosed mica schists. They grow in hexagonal crystals. The most valuable emeralds for gems are transparent rather than opaque, have few inclusions, and are a dark shade of green. Emeralds usually have quite a lot of inclusions, so sometimes people use oil to hide them, but looking at the inclusions can help you tell where the emerald came from. One final fun fact: There is even a faceting method called the emerald cut, which has a rectangular face with 8 sides. It is also known as the octagon cut. The emerald cut works well on emeralds but can be used on any gemstone, even diamonds.

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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!