Miargyrite

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Miargyrite
Miargyrite and Quartz - Red Mountain, Randsburg, California, USA.jpg
Miargyrite, a group of tabular crystals (size approx. 1.5 mm) grown on quartz
General and classification
chemical formula AgSbS 2
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.HA.10 ( 8th edition : II / C.16)
07/03/03/02
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol 2 / m
Space group C 2 / c
Lattice parameters a  = 12.862  Å ; b  = 4.409 Å; c  = 13.218 Å
β  = 98.48 ° Please complete the source as an individual reference!
Formula units Z  = 8 Please complete the source as an individual reference!
Physical Properties
Mohs hardness 2 to 2.5
Density (g / cm 3 ) 5.18 to 5.25
Cleavage {010} imperfect
Break ; Tenacity uneven, mussel-like
colour Gray
Line color red
transparency opaque
shine diamond gloss
Crystal optics
Refractive index n  = 2.720 to 2.800

Miargyrite , also silver antimony luster or hemiprismatic ruby ​​blende, is a rarely occurring mineral from the mineral group of sulfides and sulfosalts . It crystallizes in the monoclinic crystal system with the chemical composition AgSbS 2 and forms thick, massive crystals of up to one centimeter in size from black to gray in color.


Etymology and history

The mineral was first found in 1824 by Friedrich Mohs in the type locality , the New Hope God mine in Bräunsdorf, today a district of Oberschöna in Saxony . Since he the new mineral of Rotgültigerz or ruby orifice (now Pyrargyrite separated), he called it initially Hemiprismatische Rubin panel . The current name Miargyrite was given to the mineral by Heinrich Rose , who was the first to examine it more closely. He named it after the Greek words argyros (silver) and meion (less), since miargyrite contains less silver than pyrargyrite.

classification

In the Strunz system , miargyrite is classified as sulfides and sulfosalts. It is counted among the sulphides with a ratio of metal to sulfur, selenium or tellurium of 1: 1. In the eighth edition , it formed a group with aramayoite , tree starchite , bohdanowiczite , cuboargyrite , matildite , schapbachite and volynskite . In the ninth edition, it is one of the sulfosalts with tin (II) sulfide as a model, which contain copper , silver or iron , but no lead .

In the systematics of minerals according to Dana , miargyrite and smithite form a subgroup of sulfosalts with the ratio z / y = 2 and the composition (A + ) i (A 2+ ) j [B y C z ], A = metals, B = Semi-metals, C = non-metals.

Modifications and varieties

The compound AgSbS 2 is trimorphic and, in addition to miargyrite, can also crystallize in a triclinic structure as tree starch and in a cubic structure as cuboargyrite .

Education and Locations

Group of two miargyrite crystals (size of the largest crystal approx. 1.7 mm) grown on quartz

Miargyrite forms under hydrothermal conditions at low temperatures. It is associated with tree starchite, prostite , pyrargyrite, polybasite , silver, galena , sphalerite , pyrite , quartz , calcite and barite .

The mineral occurs in many mines, but mostly only in small quantities and rarely as the main ore. The sites include the Harz Mountains and other sites in Germany , Příbram and Třebsko in the Czech Republic , Baia Sprie in Romania , Hiendelaencina in Spain , the Altai in Russia , Rajasthan in India , at Brandywine Creek in Canada , in the US states of Idaho and California , Real de Catorce , Sombrerete and Veta Grande in Mexico , Copiapó and Huantajaya in Chile , Colquechaca and Cerro Rico in Bolivia, and Huancavelica and Julcani in Peru .

morphology

Miargyrite crystals are flattened along {001}, {100} or {101}. They are striped along [010] and [011] next to it.

Crystal structure

Miargyrite crystallizes in the monoclinic crystal system in the space group C 2 / c with the lattice parameters a  = 12.862  Å ; b  = 4.409 Å; c  = 13.218 Å and β = 98.48 ° as well as eight formula units per unit cell .

use

Miargyrite is a silver ore if it occurs in sufficient quantities or together with other ores.

See also

Individual evidence

  1. ↑ Heinrich Rose: About the naturally occurring non-oxidized compounds of antimony and arsenic. In: Poggendorff's annals of physics and chemistry. 1829, 15, pp. 469-470.
  2. ^ List of minerals according to Dana at webmineral.com

literature

  • Miargyrit in: Anthony et al .: Handbook of Mineralogy , 1990, 1, 101 ( pdf ).

Web links

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