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About ChlorastroliteHide

Ca2MgAl2(Si2O7)(SiO4)(OH)2 · H2O
Green star stone. First discovered on Isle Royale, Lake Superior by C. T. Jackson and J. D. Whitney in 1847.
A variety of Pumpellyite-(Mg)

Chatoyant and generally exhibits a distinctive and attractive mosaic or segmented pattern, sometimes referred to as "turtleback". State gemstone of Michigan.
Originally described from Isle Royale National Park, Lake Superior, Keweenaw Co., Michigan, USA.

Visit gemdat.org for gemological information about Chlorastrolite.

Chemical Properties of ChlorastroliteHide

Ca2MgAl2(Si2O7)(SiO4)(OH)2 · H2O

Synonyms of ChlorastroliteHide

Other Language Names for ChlorastroliteHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
3 photos of Chlorastrolite associated with Thomsonite-CaNaCa2[Al5Si5O20] · 6H2O

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for ChlorastroliteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Norman King Huber(1975)
The geologic story of Isle Royale National Park.
United States Geological Survey Bulletin 1309

Internet Links for ChlorastroliteHide

Localities for ChlorastroliteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • Michigan
    • Houghton Co.
      • Hancock
      • Ripley
    • Keweenaw Co.
      • Central
Mineralogy of Michigan (2004) Heinrich & Robinson
Mineralogy of Michigan (2004) Heinrich & Robinson
Mineralogy of Michigan (2004) Heinrich & Robinson
Mineralogy of Michigan (2004) Heinrich & Robinson
      • Copper Harbor
        • Mosquito Mining District
Personally collected by Paul Brandes in 2013
      • Delaware
Bornhorst & Rose (1994) Self-guided geological field trip to the Keweenaw Peninsula, Michigan. Institute Lake Superior Geology proceedings vol 40 part 2
      • Lake Superior
USGS Bull 1309
Gems and Minerals of America- Jay Ellis Ransom-1974
Mineralogy of Michigan (2004) Heinrich & Robinson
Mineralogy of Michigan (2004) Heinrich & Robinson
Mineralogy of Michigan (2004) Heinrich & Robinson
      • Mandan
Mineralogy of Michigan (2004) Heinrich & Robinson
      • Phoenix
Bornhorst, T. J., & Barron, R. J. (2011). Copper deposits of the western Upper Peninsula of Michigan. The Geological Society of America Field Guide 24, 83-99.
self collected at site, and verified through red metal minerals
Yalmer Primeau collection
Mineral and/or Locality  
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