Larimar

Larimar is the tradename for a rare blue variety of the silicate mineral pectolite found only in the Dominican Republic, around the city of Barahona. Its coloration varies from... Wikipedia

• Category:  Inosilicate mineral
• Formula, (repeating unit):  NaCa 2Si 3O 8(OH)
• Crystal system:  Triclinic
• Crystal class:  Pinacoidal (1), (same H-M symbol)
• Space group:  P 1
• Unit cell:  a
• Color:  Shades of blue, blue-green
• Crystal habit:  Tabular to acicular, radiating fibrous, spheroidal, or columnar, massive
• Twinning:  Twin axis with composition plane, common
• Cleavage:  Perfect on
• Fracture:  Uneven
• Tenacity:  Brittle, tough when compact
• Mohs scale hardness:  4.5 - 5
• Luster:  Silky, subvitreous
• Diaphaneity:  Translucent to opaque
• Specific gravity:  2.84 - 2.90
• Optical properties:  Biaxial (+)
• Refractive index:  n α
• Birefringence:  δ
• 2V angle:  Measured: 50° to 63°, Calculated: 42° to 60°
• Dispersion:  r > v weak to very strong
• Data source:  DuckDuckGo