Isle Royale greenstone, this state's official gem, is found on Isle Royale in Lake Superior
The 
MN State gem: Beautiful Lake Superior Agates - found on both north (MN) and... [DOC] [TLE] Chlorastrolite: Rocks, Fossils & Minerals | eBay [PAR] CHLORASTROLITE & COPPER Keweenaw Lake Superior Isle Royale ... to as 
THE ISLE ROYALE GREENSTONE which is also the STATE GEM OF MICHIGAN
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