Sugilite | |
---|---|
General | |
Category | Cyclosilicate |
Formula (repeating unit) | KNa2(Fe,Mn,Al)2Li3Si12O30 |
IMA symbol | Sug [1] |
Strunz classification | 9.CM.05 |
Dana classification | 63.02.01a.09 |
Crystal system | Hexagonal |
Crystal class | Dihexagonal dipyramidal (6/mmm) H-M symbol: (6/m 2/m 2/m) |
Space group | P6/mcc |
Unit cell | a = 10, c = 14 [Å]; Z = 2 |
Identification | |
Color | Light brownish-yellow, purple, violet, reddish violet, pale pink, colorless |
Crystal habit | Prismatic crystals, typically granular to massive |
Cleavage | Poor on {0001} |
Mohs scale hardness | 6–6+1⁄2 |
Luster | Vitreous |
Streak | White |
Diaphaneity | Transparent to translucent |
Specific gravity | 2.74 |
Optical properties | Uniaxial (−) |
Refractive index | nω = 1.610 nε = 1.607 |
Birefringence | δ = 0.003 |
Pleochroism | Weak |
References | [2] [3] [4] |
Sugilite ( /ˈsuːɡəlaɪt, -dʒi-/ SOO-gə-lyte, -jee-) [2] [3] is a relatively rare pink to purple cyclosilicate mineral with the complex chemical formula K Na2( Fe, Mn, Al)2 Li3 Si12 O30. Sugilite crystallizes in the hexagonal system with prismatic crystals. The crystals are rarely found and the form is usually massive. It has a Mohs hardness of 5.5–6.5 and a specific gravity of 2.75–2.80. It is mostly translucent. Sugilite was first described in 1944 by the Japanese petrologist Ken-ichi Sugi (1901–1948) for an occurrence on Iwagi Islet, Japan, where it is found in an aegirine syenite intrusive stock. It is found in a similar environment at Mont Saint-Hilaire, Quebec, Canada. In the Wessels mine in Northern Cape Province of South Africa, sugilite is mined from a strata-bound manganese deposit. It is also reported from Liguria and Tuscany, Italy; New South Wales, Australia and Madhya Pradesh, India. [4]
Sugilite is commonly pronounced with a soft "g", as in "ginger". However, as with most minerals, its pronunciation is intended to be the same as the person it is named after; in this case, the Japanese name Sugi has a hard "g", as in "geese". [5]
The mineral is also referred to as lavulite, luvulite, and royal azel by gem and mineral collectors. [3]
In Japan, sugilite is found as yellowish-white to colourless, and is not good for jewellery. [6]
Sugilite | |
---|---|
General | |
Category | Cyclosilicate |
Formula (repeating unit) | KNa2(Fe,Mn,Al)2Li3Si12O30 |
IMA symbol | Sug [1] |
Strunz classification | 9.CM.05 |
Dana classification | 63.02.01a.09 |
Crystal system | Hexagonal |
Crystal class | Dihexagonal dipyramidal (6/mmm) H-M symbol: (6/m 2/m 2/m) |
Space group | P6/mcc |
Unit cell | a = 10, c = 14 [Å]; Z = 2 |
Identification | |
Color | Light brownish-yellow, purple, violet, reddish violet, pale pink, colorless |
Crystal habit | Prismatic crystals, typically granular to massive |
Cleavage | Poor on {0001} |
Mohs scale hardness | 6–6+1⁄2 |
Luster | Vitreous |
Streak | White |
Diaphaneity | Transparent to translucent |
Specific gravity | 2.74 |
Optical properties | Uniaxial (−) |
Refractive index | nω = 1.610 nε = 1.607 |
Birefringence | δ = 0.003 |
Pleochroism | Weak |
References | [2] [3] [4] |
Sugilite ( /ˈsuːɡəlaɪt, -dʒi-/ SOO-gə-lyte, -jee-) [2] [3] is a relatively rare pink to purple cyclosilicate mineral with the complex chemical formula K Na2( Fe, Mn, Al)2 Li3 Si12 O30. Sugilite crystallizes in the hexagonal system with prismatic crystals. The crystals are rarely found and the form is usually massive. It has a Mohs hardness of 5.5–6.5 and a specific gravity of 2.75–2.80. It is mostly translucent. Sugilite was first described in 1944 by the Japanese petrologist Ken-ichi Sugi (1901–1948) for an occurrence on Iwagi Islet, Japan, where it is found in an aegirine syenite intrusive stock. It is found in a similar environment at Mont Saint-Hilaire, Quebec, Canada. In the Wessels mine in Northern Cape Province of South Africa, sugilite is mined from a strata-bound manganese deposit. It is also reported from Liguria and Tuscany, Italy; New South Wales, Australia and Madhya Pradesh, India. [4]
Sugilite is commonly pronounced with a soft "g", as in "ginger". However, as with most minerals, its pronunciation is intended to be the same as the person it is named after; in this case, the Japanese name Sugi has a hard "g", as in "geese". [5]
The mineral is also referred to as lavulite, luvulite, and royal azel by gem and mineral collectors. [3]
In Japan, sugilite is found as yellowish-white to colourless, and is not good for jewellery. [6]