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 bluish white, light-blue, light-green, green-blue, turquoise blue, turquoise green, turquoise blue-green, deep green, dark green, to deep blue, dark blue and purple, violet and indigo and the larimar can come in many varieties and color mixes.
| Larimar (Blue Pectolite) | |
|---|---|
Larimar specimen from Dominican Republic | |
| General | |
| Category | Inosilicate mineral |
| Formula (repeating unit) | NaCa2Si3O8(OH) |
| Crystal system | Triclinic |
| Crystal class | Pinacoidal (1) (same H-M symbol) |
| Space group | P1 |
| Unit cell | a = 7.99 Å, b = 7.03 Å, c = 7.03 Å; α = 90.51°, β = 95.21°, γ = 102.53°; Z = 2 |
| Identification | |
| Color | Shades of blue, blue-green |
| Crystal habit | Tabular to acicular, radiating fibrous, spheroidal, or columnar; massive |
| Twinning | Twin axis [010] with composition plane [100], common |
| Cleavage | Perfect on {100} and {001} |
| 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 | nα = 1.594 - 1.610 nβ = 1.603 - 1.614 nγ = 1.631 - 1.642 |
| Birefringence | δ = 0.037 |
| 2V angle | Measured: 50° to 63°, Calculated: 42° to 60° |
| Dispersion | r > v weak to very strong |
| References | |
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