Chlorastrolite, (variety of pumpellyite) is a green or bluish green stone, usually with finely radiated or stellate masses. Stellate masses tend to be chatoyant. Can be subtranslucent to opaque. -- Ca₂(Mg,Fe)A_l2(SiO₄)(Si₂O₇)(OH)₂H₂O. In gemology, chatoyancy is an optical reflectance effect seen in certain gemstones. ...

Other Names

• Green starstone - especially in Michigan's Upper Peninsula.
• Greenstone (e.g., Isle Royal greenstone & Lake Superior greenstone) - misnomer(s) applied locally on the Keweenaw Peninsula of Michigan.
• Turtle back - name sometimes given because of the overall pattern, particularly polished pieces, which roughly resembles that of turtles' backs.
• Uigite - variety found on the island of Skye off the coast of Scotland.
• Zonochlorite - misnomer sometimes given rounded masses of chlorastrolite within or weathered out of amygdaloidal cavities, especially those from the area around Neepigon Bay (on Lake Superior), Ontario, Canada. Confusion may derive from the fact that Zonochlorite is sold as faux Chlorastrolite.

State nickname: Wolverine State or Great Lakes State Other U.S. States Capital Lansing Largest city Detroit Governor Jennifer Granholm Official languages English Area 250,941 km² (11th)  - Land 147,255 km²  - Water 103,687 km² (41. ... The Upper Peninsula of Michigan, also known as The Upper Peninsula, The U.P. (or The UP), and Above the Bridge by Michiganders, refers to the northern peninsula of the U.S. state of Michigan. ... The Great Lakes from space; Lake Superior is on the upper left Lake Superior is the largest of North Americas Great Lakes. ... The Keweenaw Peninsula is the most northern part of Michigans Upper Peninsula. ... The Old Man of Storr, Skye The Isle of Skye, usually known simply as Skye (Scottish Gaelic: An t-Eilean Sgiathanach) is the largest and most northerly island in the Inner Hebrides of Scotland. ... Scotland (Alba in Scottish Gaelic) is a country or nation and former independent kingdom of northwest Europe, and one of the four constituent parts of the United Kingdom. ... The Great Lakes from space; Lake Superior is on the upper left Lake Superior is the largest of North Americas Great Lakes. ... Motto: Ut Incepit Fidelis Sic Permanet (Loyal she began, loyal she remains) Other Canadian provinces and territories Capital Toronto Largest city Toronto Lieutenant Governor James K. Bartleman Premier Dalton McGuinty (Liberal) Area 1,076,395 km² (4th)  - Land 917,741 km²  - Water 158,654 km² (14. ...

Occurrences

As amygdaloids and fracture fillings in basic igneous rocks and as pebbles and granules in loose sediments, such as beach gravels, derived from those rocks.

Misc.

• Chlorastrolite, designated by the misnomer greenstone, is the official state gemstone of Michigan.
• Chlorastrolite was once thought to be an impure variety of prehnite or thomsonite.