$220Median
24Sold (12 mo)
$120Last sale
Idocrase specimens for sale
27 for sale · $135–$9,000 USD
213 in the gallery
Idocrase is a calcium-iron-aluminum inosilicate mineral that forms in metamorphic rocks and contact aureoles. Crystals are typically prismatic to blocky, often showing a vitreous to pearly luster and a green to olive-brown color. The mineral commonly crystallizes in granular to compact aggregate habits, and may occur as platy or faceted crystals in well-formed specimens. Notable localities include classic deposits in the United States and Canada, with additional finds in Mali contributing to its rarity in hand specimens.
- Formula
- Ca19Fe3+Al4(Al6Mg2)(◻4)◻[Si2O7]4[(SiO4)10]O(OH)9
- Rarity
- Common
- Stability
- Stable
- Collector interest
- Moderate Interest
- Classification notes
- Silicate; Epidote group (sorosilicate)
Key characteristics
- Crystal system
- tetragonal
- Mohs hardness
- 6–7
- Specific gravity
- 3.32–3.47
- Luster
- vitreous, resinous, greasy
- Transparency
- transparent, translucent, opaque
- Color
- green, brown, yellow, blue, red, pink, violet, gray, white
- Streak
- white
- Cleavage
- poor
- Fracture
- conchoidal, uneven
- Crystal habit
- prismatic, pyramidal, granular, massive
- Gem mineral
- Classic / historic
Buy Idocrase specimens
View all 27Where Idocrase is found
Top localities
- Jeffrey Mine88 specimens
- Bellecombe14 specimens
- Sierra de Cruces11 specimens
- Belvidere Mountain Quarries6 specimens
- Aosta Valley2 specimens
- Crestmore quarries2 specimens
- Ala Valley1 specimen
- Alchuri1 specimen
- Bafoulabé Cercle1 specimen
- Coahuila1 specimen
About Idocrase
Collectors prize Idocrase for its rich, sometimes lustrous crystals and its distinctive green hues that contrast with more common metamorphic minerals. Specimens from well-known localities often display good transparency, pleasing color zoning, and sharp termination faces, making them attractive for display and study. Its geological occurrence highlights the interplay of metamorphism and mineral chemistry, appealing to collectors who value both aesthetics and the scientific background of mineral formation.
