Discover authentic Isle Royale greenstone—Michigan's official state gem—preserved within its original basalt matrix. This chlorastrolite specimen showcases nature's artistry, formed millennia ago in the volcanic landscapes of the Keweenaw Peninsula. Whether displayed as a striking natural specimen or carefully extracted with tools of your choice, each piece reveals the gem's distinctive character. With a hardness rating of 5-6 on the Mohs scale, greenstone offers both geological significance and tactile beauty for the discerning collector.