Goslarite

Goslarite is a hydrated zinc sulfate mineral (ZnSO₄ · 7 H₂O) which was first found in the Rammelsberg mine, Goslar, Harz, Germany. It was described in 1847. Goslarite belongs to the epsomite group which also includes epsomite (MgSO₄ · 7 H₂O) and morenosite (NiSO₄ · 7 H₂O). Goslarite is an unstable mineral at the surface and will dehydrate to other minerals like bianchite (ZnSO₄ · 6 H₂O), boyleite (ZnSO₄ · 4 H₂O) and gunningite (ZnSO₄ · H₂O).

Goslarite
Goslarite on display at the Museo Nacional de Ciencias Naturales
General
Category	Sulfate mineral
Formula (repeating unit)	ZnSO4 · 7 H2O
IMA symbol	Gos[1]
Strunz classification	7.CB.40
Crystal system	Orthorhombic
Crystal class	Disphenoidal (222) (same H-M symbol)
Space group	P212121
Unit cell	a = 11.8176 Å, b = 12.0755 Å c = 6.827 Å, Z = 4
Identification
Formula mass	287.56 g/mol
Color	Colorless, pinkish, white, greenish, green, blue, green blue, bluish and brownish
Crystal habit	Acicular, massive, stalactitic
Cleavage	{010} perfect
Fracture	Conchoidal
Tenacity	Brittle
Mohs scale hardness	2.0–2.5
Luster	Vitreous (glassy)
Streak	White
Specific gravity	1.96
Optical properties	Biaxial (-)
Refractive index	nα = 1.447 - 1.463 nβ = 1.475 - 1.480 nγ = 1.470 - 1.485
Birefringence	δ = 0.0220–0.0230
Pleochroism	none
2V angle	46°
References	[2][3][4][5]

Physical properties

The composition of goslarite was determined by the US National Bureau of Standards (now the National Institute of Standards and Technology) in 1959 as follows: SO₃ 27.84 wt%, ZnO 28.30 wt% and H₂O 43.86 wt%.

Goslarite's cleavage is perfect in {010}, as for epsomite and morenosite. The color of goslarite ranges from brownish to pinkish, blue, brown, colorless, green and green blue. The luster ranges from vitreous to nacreous and silky (if fibrous). Goslarite is soluble in water, has an astringent taste, and is strongly diamagnetic.^[6][7][8]

Geologic occurrence

Goslarite is formed from the oxidation of sphalerite ((Zn, Fe)S).^[9] It was first found in Rammelsberg mine, Goslar, Harz, Germany. It often occurs as an efflorescence on timbers and walls of mine passages. Goslarite is widespread as a post mining efflorescence in mines that contain sphalerite or any zinc minerals.

Economical uses

In the pharmaceutical industry it is used as a direct emetic, antiseptic and disinfectant.^[10]

References

1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
2. Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (eds.). "goslarite". Handbook of Mineralogy (PDF). Chantilly, VA, US: Mineralogical Society of America. ISBN 0962209716.
3. Goslarite on Mindat
4. Goslarite data on Webmineral
5. Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0-471-80580-7
6. Dana, J.D. (1854). A System of Mineralogy Comprising The Most Recent Discoveries. New York: Putnam. p. 384.
7. Egleston, T (1871). Catalogue of Minerals, with Their Formulae and Crystalline Systems: Prepared for the Use of the Students of the School of Mines, of Columbia College. Columbia: Angell. p. 173.
8. Palache (1944). The System of Mineralogy. New York: John Wiley & Sons. pp. 513–516.
9. Gaines, RV (1997). Dana's New Mineralogy. New York: John Wiley & Sons. p. 819. ISBN 0471193100.
10. Carretero, MI; Pozo, Manuel (2009). "Clay and non-clay minerals in the pharmaceutical and cosmetic industries Part II. Active ingredients". Applied Clay Science. 47 (3–4): 171–181. doi:10.1016/j.clay.2009.10.016.

External links

• Mineral Picture