Hendricksite
Hendricksite | |
---|---|
General | |
Category | Mineral |
Formula (repeating unit) | KZn3(Si3Al)O10(OH)2 |
IMA symbol | Hds[1] |
Strunz classification | 09.EC.20 |
Dana classification | 71.2.2b.6 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) |
Space group | B2/m |
Unit cell | 499.58 ų |
Identification | |
Formula mass | 493.25 |
Color | Copper-, bronze brown, dark reddish brown to reddish black |
Cleavage | Perfect on {001} |
Mohs scale hardness | 2.5 - 3 |
Diaphaneity | Translucent |
Specific gravity | 2.86 - 3.43 |
Optical properties | Biaxial (-) |
Refractive index | nα = 1.598 - 1.624 nβ = 1.658 - 1.686 nγ = 1.660 - 1.697 |
Birefringence | 0.062 - 0.073 |
Pleochroism | X = pale yellow, Y = light chestnut brown, Z = light chestnut brown |
2V angle | Measured 2°- 8°, calculated 20°- 44° |
Dispersion | Slight, r < v |
Common impurities | Ti, Fe, Ca, Ba, Li, Na, F |
Hendricksite is a member of the trioctahedral micas group. The mineral was named by Clifford Frondel and Jun Ito in honor of Sterling Brown Hendricks, who studied micas. Zinc in the formula can be replaced with manganese(II) or magnesium. Currently, this is the only mica known for its zinc dominancy.[2] It was approved in 1966 by the IMA. It has a barely detectable, 1% radioactivity measured by GRapi (Gamma Ray American Petroleum Institute Units). It mostly consists of oxygen (38.92%), zinc (18.56%), silicon (15.37%) and manganese (10.02%), but otherwise contains potassium (7.13%) which gives the gem its irradiative attributes, aluminium (7.11%), magnesium (2.46%) and hydrogen (0.41%). It has pleochroic attributes, which is an optical phenomenon that makes gems to be seen a different color depending on the axis it is seen. On the X axis, it can be seen in a pale brown color, while on the Y and Z axis it is seen in a light chestnut brown color.[3]
References[]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85: 291–320.
- ^ "Hendricksite". www.mindat.org. Retrieved 2021-02-11.
- ^ "Hendricksite Mineral Data". webmineral.com. Retrieved 2021-02-11.
- Zinc minerals
- Mica group
- Phyllosilicates
- Mineral stubs