Jerrygibbsite
Jerrygibbsite is a rare silicate mineral with the chemical formula (Mn,Zn)9(SiO4)4(OH)2. Jerrygibbsite was originally discovered by Pete J. Dunn in 1984, who named it after mineralogist Gerald V. Gibbs (born 1929). It has only been reported from the type locality of Franklin Furnace, New Jersey, United States, and in Namibia's Otjozondjupa region. Jerrygibbsite is member of the leucophoenite family of the humite group. It is always found with these two minerals. It is a dimorph of sonolite.
| Jerrygibbsite | |
|---|---|
Jerrygibbsite (pink) found in New Jersey | |
| General | |
| Category | Nesosilicates |
| Formula (repeating unit) | (Mn,Zn)9(SiO4)4(OH)2 |
| IMA symbol | Jgb |
| Strunz classification | 9.AF.70 |
| Crystal system | Orthorhombic |
| Crystal class | Pyramidal (mm2) H-M symbol: (mm2) |
| Space group | Pbn21 |
| Unit cell | a = 4.85, b = 10.7 c = 28.17 [Å]; Z = 4 |
| Identification | |
| Color | Violet-pink, with a brownish tinge |
| Crystal habit | Interlocking anhedral crystals |
| Cleavage | Imperfect on {001} |
| Mohs scale hardness | 5.5 |
| Luster | Vitreous |
| Streak | Light pink |
| Diaphaneity | Alternating transparent and translucent lamellae |
| Specific gravity | 4.00 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.772 nβ = 1.783 nγ = 1.789 |
| Birefringence | δ = 0.017 |
| 2V angle | Measured: 72° |
| References | |
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