Chlorastrolite

E763160

Chlorastrolite is a green, star-patterned variety of pumpellyite best known as a semi-precious gemstone found in the Lake Superior region.

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Statements (49)

Predicate Object
instanceOf mineraloid variety
semi-precious gemstone
variety of pumpellyite
associatedWith amygdaloidal basalt
metamorphosed basalt
chemicalFormula Ca2(Mg,Fe)Al2(SiO4)(Si2O7)(OH)2·H2O
color bluish-green
green
containsElement aluminum
calcium
hydrogen
iron
magnesium
oxygen
silicon
formationEnvironment hydrothermal alteration of basalt
low-grade metamorphic
foundIn beach pebbles of Lake Superior
vesicles in basalt
fracture uneven
hardnessMohs 5.5–6
hasPattern star pattern
stellate pattern
turtleback pattern
luster silky
vitreous
mineralGroup pumpellyite group
nickname greenstone
turtleback stone
occursIn Copper Country, Michigan, USA NERFINISHED
Isle Royale, Michigan, USA NERFINISHED
Keweenaw Peninsula, Michigan, USA NERFINISHED
Lake Superior region NERFINISHED
opticalProperty chatoyancy-like effect
radial fibrous structure
rarity relatively rare
specificGravity 3.2–3.4
stateGem Michigan NERFINISHED
stateGemDesignationYear 1972
system monoclinic
tenacity tough
transparency opaque
translucent
typicalCut cabochon
usedAs gemstone
usedFor cabochons
jewelry
valueFactor intensity of green color
sharpness of star pattern

Referenced by (5)

Full triples — surface form annotated when it differs from this entity's canonical label.

Michigan hasStateGem Chlorastrolite
Michigan hasOfficialGemstone Chlorastrolite
Michigan hasOfficialGemstone Chlorastrolite
Michigan stateGem Chlorastrolite
Michigan hasOfficialGemstone Chlorastrolite