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Niigataite
A valid IMA mineral species
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About Niigataite
Flag of Niigata prefecture, Japan
Formula:
(CaSr)(AlAlAl)O[Si2O7][SiO4](OH)
Colour:
Pale grey to yellowish green
Lustre:
Vitreous
Hardness:
5 - 5½
Specific Gravity:
3.63 (Calculated)
Crystal System:
Monoclinic
Member of:
Name:
Named for Niigata prefecture, Japan, that includes the type locality.
Originally known as niigataite; renamed "Clinozoisite-(Sr)" by the Epidote Subcommittee of the CNMMN in 2006; reverted back to Niigataite in 2015.
Unique Identifiers
Mindat ID:
11460
Long-form identifier:
mindat:1:1:11460:0
IMA Classification of Niigataite
Approved
IMA Formula:
CaSrAl3(Si2O7)(SiO4)O(OH)
Approval year:
2001
First published:
2003
Type description reference:
Miyajima, Hiroshi, Matsubara, Satoshi, Miyawaki, Ritsuro, Hirokawa, Kazuo (2003) Niigataite, CaSrAl3(Si2O7)(SiO4)O(OH): Sr-analogue of clinozoisite, a new member of the epidote group from the Itoigawa-Ohmi district, Niigata Prefecture, central Japan. Journal of Mineralogical and Petrological Sciences, 98 (3) 118-129 doi:10.2465/jmps.98.118
Classification of Niigataite
9.BG.05
9 : SILICATES (Germanates)
B : Sorosilicates
G : Sorosilicates with mixed SiO4 and Si2O7 groups; cations in octahedral [6] and greater coordination
9 : SILICATES (Germanates)
B : Sorosilicates
G : Sorosilicates with mixed SiO4 and Si2O7 groups; cations in octahedral [6] and greater coordination
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Nii | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Niigataite
Vitreous
Transparency:
Transparent
Colour:
Pale grey to yellowish green
Streak:
White
Hardness:
5 - 5½ on Mohs scale
Hardness Data:
Measured
Tenacity:
Brittle
Cleavage:
Perfect
on {001}
on {001}
Density:
3.63 g/cm3 (Calculated)
Optical Data of Niigataite
Type:
Biaxial
Comments:
1.67 < n <1.725, anomalous violet interference color.
Chemistry of Niigataite
Mindat Formula:
(CaSr)(AlAlAl)O[Si2O7][SiO4](OH)
Element Weights:
Common Impurities:
Fe
Ohmi river, Ōmi, Itoigawa City, Niigata Prefecture, Japan