Epsomit

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Epsomit
Epsomite.jpg
Epsomit in a cave in New Mexico
General and classification
other names

Epsom salt

chemical formula Mg [SO 4 ] • 7H 2 O
Mineral class
(and possibly department) 		Water-containing sulfates without foreign anions
System no. to Strunz
and to Dana 		7.CB.40 ( 8th edition : VI / C.03d)
06/29/11/01
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-disphenoidic; 222
Space group P 2 1 2 1 2 1 (No. 19)Template: room group / 19
Lattice parameters a  = 11.88  Å ; b  = 12.00 Å; c  = 6.86 Å
Formula units Z  = 4
Twinning rarely after {110}
Physical Properties
Mohs hardness 2 to 2.5
Density (g / cm 3 ) measured (synthetic): 1.677; calculated: 1.677
Cleavage completely after {010}, clearly after {101}
Break ; Tenacity shell-like
colour colorless, white, yellow-white, green-white, pink-white
Line color White
transparency transparent to translucent
shine Glass gloss, silk gloss, matt
Crystal optics
Refractive indices n α  = 1.433
n β  = 1.455
n γ  = 1.461
Birefringence δ = 0.028
Optical character biaxial negative
Axis angle 2V = 52 ° (measured); 54 ° (calculated)
Other properties
Chemical behavior Easily soluble in water, bitter taste

Epsomite , also known as Epsom salt or under its chemical name magnesium sulfate heptahydrate because of its bitter taste , is a frequently occurring mineral from the mineral class of " sulfates ( and relatives )". It crystallizes in the orthorhombic crystal system with the chemical composition Mg [SO 4 ] · 7H 2 O and develops mostly granular or fibrous aggregates and crusts, rarely also needle-like to prismatic crystals of white color with a yellowish, greenish or pinkish tinge. Colorless epsomite is also known.

Epsomit forms with goslarite and morenosite each a gapless mixed crystal row .

Etymology and history

Epsomit was named in 1824 after its first place of discovery, the English town of Epsom . However, it was known and first described as early as 1806 as a deposit in connection with the mineral water found in Epsom .

classification

Already in the outdated, but still in use 8th edition of the mineral classification according to Strunz , the epsomite belonged to the mineral class of "sulfates, chromates, molybdates, wolframates" (and other relatives) and there to the section "hydrous sulfates without foreign anions ", where it was classified as Namesake of the "Epsomit series" together with the system no. VI / C.03d and the other members fauserite (discredited), goslarite , morenosite , tauriscite (Q).

In the last revised and updated Lapis mineral directory by Stefan Weiß in 2018 , which, out of consideration for private collectors and institutional collections, is still based on this classic system of Karl Hugo Strunz , the mineral was given the system and mineral number. VI / C.07-10 . In the “Lapis system” this also corresponds to the section “Hydrous sulfates, without foreign anions”, where epsomite, together with goslarite , meridianite and morenosite, forms an independent but unnamed group.

The 9th edition of Strunz's mineral systematics , which has been valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, classifies the epsomite in the category of "sulfates (selenates etc.) without additional anions, with H 2 O". However, this is further subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in the sub-section “With only medium-sized cations”, where it is named after the “epsomite group” with the system no. 7.CB.40 and the other members Goslarit and Morenosit.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , also assigns epsomite to the class of "sulfates, chromates, molybdates" (and other relatives) and there in the department of "water-containing acids and sulfates". Here, too, he is the namesake of the " Epsomit group " with the system no. 29/06/11 and the other members and goslarite Morenosit within the subdivision "Water-containing acids and sulfates AXO 4 × x (H 2 to find O)".

Crystal structure

Epsomit crystallizes orthorhombically in the space group P 2 1 2 1 2 1 (space group no. 19) with the lattice parameters a  = 11.88  Å ; b  = 12.00 Å and c  = 6.86 Å and 4 formula units per unit cell . Template: room group / 19

Modifications and varieties

An iron-containing epsomite is called a tauriscite .

Education and Locations

Spotted Lake in the southern Canadian province of British Columbia, one of several drainless basins in the region, at the deepest point of which sulphatic deposits with u. a. Form Epsomit.

Epsomit occurs in many places, but mostly only in small quantities. As a secondary mineral , it arises from the oxidation of metal sulfides . Epsomit is also primarily formed through precipitation in salt lakes and marine concentration basins . It is one of the relatively poorly water-soluble precious salts and is therefore mainly accompanied by halite (rock salt) in these cases .

Localities with secondary education are mines in sulphidic ore deposits, inter alia, the copper mines of Bisbee in Arizona and several mines in Nevada . Fossil primary formations of epsomite can be found in numerous potash salt deposits such as in the Zechstein Salinar ( Upper Permian ) in Central Europe. It occurs as a recent primary formation in so-called Spotted Lakes in Okanogan County in the north of the US state of Washington and across the Canadian border in southern British Columbia . A recently he also forms from the weathering of pyrite containing Metapelits at the "Alum Cave Bluff" in the Great Smoky Mountains National Park , Sevier County , Tennessee , United States , where he together with Apjohnit the rare earth - sulphate - Oxalatminerale Coskrenit- (Ce ) , Zugshunstit- (Ce) and Levinsonite- (Y) at their type locality . Also in the immediate vicinity of subaeric volcanic exhalations ( fumaroles ), e.g. B. on Vesuvius , Epsomit falls out recently.

Outside of the earth, Epsomit is likely to occur at least everywhere where aqueous solutions can or once could exist. So Epsomit was actually detected on the surface of Jupiter's moon Europa , but not directly, but from the earth with the help of spectral analyzes . On Mars still no Epsomite has so far been discovered, however, come in the Martian soil proven relatively large amounts of magnesium sulfate before, and it is very likely that these deposits also contain Epsomite.

Further naturally occurring hydrates of magnesium sulfate are kieserite , pentahydrite and hexahydrite . These are the mono-, penta- or hexahydrate.

use

In the medicine

Epsomit, like other water-soluble sulfates ( Mirabilit , Kieserit), can be used as a laxative .

Precautions

Epsomit, like mirabilit , is not stable. It can give off water in dry conditions. If the humidity is too high, epsomite crystals dissolve .

See also

literature

Web links

Commons : Epsomite  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  384 (English).
  2. ↑ a b Epsomite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 68  kB ; accessed on September 1, 2019]).
  3. ↑ a b c d e Epsomite. In: mindat.org. Hudson Institute of Mineralogy, accessed September 1, 2019 .
  4. ↑ a b Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
  5. ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed September 1, 2019 .
  6. ^ Olaf Pitt Jenkins: Spotted lakes of epsomite in Washington and British Columbia . In: American Journal of Science . 4th row, volume 46 , 1918, pp. 638–644 , doi : 10.2475 / ajs.s4-46.275.638 (English).
  7. ^ WAG Bennett: Saline Lake Deposits in Washington . In: Washington Division of Mines and Geology Bulletin . tape 49 , 1962, pp. 102 (English, file.dnr.wa.gov [PDF; 14.1 MB ; accessed on September 1, 2019]).
  8. ^ Robin W. Renaut, Peter R. Long: Sedimentology of the saline lakes of the Cariboo Plateau, Interior British Columbia, Canada . In: Sedimentary Geology . tape 64 , no. 4 , 1989, pp. 239-264 , doi : 10.1016 / 0037-0738 (89) 90051-1 (English).
  9. ↑ Stefan Deiters: Jupiter's moon Europe - ocean could be like earthly seas. In: astronews.com. March 16, 2013, accessed September 1, 2019 .
  10. ↑ David T. Vaniman, David L. Bish, Steve J. Chipera, Claire I. Fialips, J. William Carey, William C. Feldman: Magnesium sulphate salts and the history of water on Mars . In: Nature . tape 431 , 2004, p. 663–665 , doi : 10.1038 / nature02973 (English, researchgate.net [PDF; 331 kB ; accessed on September 1, 2019]).