Klöchite

Klöchite is a cyclosilicate mineral of the Osumilite Group, found in a basalt quarry in Klöch, Austria. The basalt quarry it was found in is part of the Styrian Basin Volcanic Field in south-eastern Austria. Klöchite was found to be hosted in a xenolith primarily composed of quartz, sanidine, and diopside. Very few vesicles in the xenolith held Klöchite crystals, and only two samples were taken for study.^[1]

Klöchite
General
Category	Osumilite
Formula	K◻2(Fe2+Fe3+)Zn3[Si12O30]
IMA symbol	Klö
Strunz classification	9.CM.05 9 : Silicates C : Cyclosilicates M : [Si6O18]12- 6-membered double rings
Crystal system	Hexagonal
Crystal class	6/mmm (6/m 2/m 2/m) - Dihexagonal Dipyramidal
Space group	P6/mcc
Unit cell	a = 10.120 Å, c = 14.298 Å
Identification
Color	Blue, Bright Orange
Cleavage	None Observed
Luster	Vitreous
Specific gravity	3.007
Density	3.007 g/cm3
Optical properties	Uniaxial negative
Refractive index	nω = 1.594 nε = 1.590
References	[1][2]

Occurrence

Klöchite was found at the Klöch volcano in south-east Austria. The town of Klöch has a basalt mine, where a SiO₂-rich xenolith protrudes. Small vesicles in the xenolith are found to host titanite, enstatite, forsterite, and other minerals including klöchite.^[1] Klöchite has also been found in the town of Porto da Cruz, Madeira, Portugal, in a gabbro outcrop.^[2]

Physical properties

Klöchite is seen as a flattened, hexagonal crystal. It has a maximum thickness of 0.01 mm and diameter of 0.3 mm. Due to a limited amount of samples, the streak and hardness were not determined for Klöchite.^[1]

Optical properties

Klöchite has a blue coloring, with a vitreous luster. It is also found to be translucent and is not fluorescent.^[2]

Chemical composition

Element	wt%	Range
Si	29.29	28.84 - 29.55
Zn	14.91	14.16 - 15.81
Fe	8.46	7.89 2 - 8.79
K	2.64	2.53 - 2.67
Mn	1.31	1.22 2 - 1.39
Na	1.09	0.88 - 1.51

^[1]

X-ray crystallography

Limited samples of Klöchite mean that powder x-ray diffraction was not able to be performed, but the group of scientists who discovered the mineral performed a simulated powder diffraction. Single crystal X-ray diffraction was carried out, and the space group P6/mcc was determined from the intensity and absences in the data. The simulated diffraction was compared to x-ray diffraction data of milarite group mineral darapiosite. Klöchite's crystal structure has a silicate tetrahedral ring structure like other cyclosilicates, with iron cation octahedra and zinc atoms connecting the silicate rings.^[1][2]

See also

• List of minerals