State Gem Chlorastrolite (literally "green star stone") is also known as greenstone or Isle Royale greenstone. Like the Petoskey stone, chlorastrolite is often crafted into unique jewelry and souvenirs. The gem ranges in color from yellow-green to almost black and when polished shows a turtleback pattern. Primarily found in the Upper Peninsula, chlorastrolite was adopted as the state gem by Public Act 56 of 1972.
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