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Hessite

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Formula:
Ag
 
2
Te
System:MonoclinicColour:lead-grey, steel-grey
Hardness:2 - 3
Name:
Named in 1843 by Frobel in honor of Germain Henri Hess [August 7, 1802 Geneva, Switzerland - November 30, 1850 St. Petersburg, Russia], Swiss-Russian chemist who proposed Hess's Law, which stated that the final thermodynamic energy of a series of chemical reactions is independent of the chemical pathway to that state. Earlier called tellursilber by Rose and later confounded with petzite and other species. Hess was a student of Jons Jakob Berzelius.


Above 155°C hessite is cubic, and on cooling below this temperature it develops fine phase transformation lamellae.

Classification of Hessite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:2/B.05-40
Nickel-Strunz 10th (pending) edition ID:2.BA.60

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
B : Metal Sulfides, M: S > 1: 1 (mainly 2: 1)
A : With Cu, Ag, Au
Dana 8th edition ID:2.4.2.1

2 : SULFIDES
4 : AmBnXp, with (m+n):p = 2:1
Hey's CIM Ref.:3.2.5

3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
2 : Sulphides etc. of Ag
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Type Occurrence of Hessite

Type Locality:Koz'modem'yanskii shaft, Second Zavodinskii Mine (Second Sawodinsk Mine), Zyryanovsk Rayon, Altai Mts (Rudnyi Altai), Eastern Kazakhstan Province (Shyghys Qazaqstan Oblysy; Vostochno-Kazakhstanskaya Oblast'), Kazakhstan
Year of Discovery:1843

Occurrences of Hessite

Geological Setting:Low to medium temperature hydrothermal deposits.

Physical Properties of Hessite

Lustre:Metallic
Diaphaneity (Transparency):Opaque
Colour:lead-grey, steel-grey
Comment:Tarnishing to black
Streak:black
Hardness (Mohs):2 - 3
Hardness (Vickers):VHN100=22 - 24 kg/mm2
Tenacity:Sectile
Cleavage:Poor/Indistinct
indistinct on {100}
Comment:Even to smooth fracture
Density (measured):8.24 - 8.45 g/cm3
Density (calculated):8.4 g/cm3

Crystallography of Hessite

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Space Group:P21/b
Space Group Setting:P21/c
Cell Parameters:a = 8.13Å, b = 4.48Å, c = 8.09Å
β = 112.9°
Ratio:a:b:c = 1.815 : 1 : 1.806
Unit Cell Volume:V 271.43 ų (Calculated from Unit Cell)
Z:4
Morphology:Pseudocubic, highly modified, massive
Twinning:twin lamellae visible in polished section

Optical Data of Hessite

Type:Anisotropic
Anisotropism:Distinct from dark orange to dark blue

Chemical Properties of Hessite

Formula:
Ag
 
2
Te
Simplified for copy/paste:Ag2Te
Essential elements:Ag, Te
All elements listed in formula:Ag, Te
Common Impurities:Au,Pb

Relationship of Hessite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
2.BA.05Chalcocite
Cu
 
2
S
2.BA.05Djurleite
Cu
 
31
S
 
16
2.BA.05Geerite
Cu
 
8
S
 
5
2.BA.05Roxbyite
Cu
 
9
S
 
5
2.BA.10Anilite
Cu
 
7
S
 
4
2.BA.10Digenite
Cu
 
9
S
 
5
2.BA.15Bornite
Cu
 
5
FeS
 
4
2.BA.20Bellidoite
Cu
 
2
Se
2.BA.20Berzelianite
Cu
 
2
Se
2.BA.25Athabascaite
Cu
 
5
Se
 
4
2.BA.25Umangite
Cu
 
3
Se
 
2
2.BA.30Rickardite
Cu
 
7
Te
 
5
2.BA.30Weissite
Cu
 
2-x
Te
2.BA.35Acanthite
Ag
 
2
S
2.BA.40Mckinstryite
Ag
 
5-x
Cu
 
3+x
S
 
4
2.BA.40Stromeyerite
AgCuS
2.BA.40dUM2003-13-S:AgAuCu
Ag
 
6
AuCu
 
2
S
 
5
2.BA.45Jalpaite
Ag
 
3
CuS
 
2
2.BA.45Selenojalpaite
Ag
 
3
CuSe
 
2
2.BA.50Eucairite
AgCuSe
2.BA.55Aguilarite
Ag
 
4
SeS
2.BA.55Naumannite
Ag
 
2
Se
2.BA.60Cervelleite
Ag
 
4
TeS
2.BA.60Chenguodaite
Ag
 
9
Fe
3+
 
Te
 
2
S
 
4
2.BA.65Henryite
Ag
 
3
Cu
 
4
Te
 
4
2.BA.65Stützite
Ag
 
5-x
Te
 
3
, x = 0.24-0.36
2.BA.70Argyrodite
Ag
 
8
GeS
 
6
2.BA.70Canfieldite
Ag
 
8
SnS
 
6
2.BA.70Putzite
(Cu
 
4.7
Ag
 
3.3
)GeS
 
6
2.BA.75Fischesserite
Ag
 
3
AuSe
 
2
2.BA.75Penzhinite
(Ag,Cu)
 
4
Au(S,Se)
 
4
2.BA.75Petrovskaite
AuAg(S,Se)
2.BA.75Petzite
Ag
 
3
AuTe
 
2
2.BA.75Uytenbogaardtite
Ag
 
3
AuS
 
2
2.BA.80Bezsmertnovite
(Au,Ag)
 
4
Cu(Te,Pb)
2.BA.80Bilibinskite
PbCu
 
2
Au
 
3
Te
 
2
2.BA.80Bogdanovite
(Au,Te,Pb)
 
3
(Cu,Fe)
Related Minerals - Hey's Index Grouping:

- +
3.2.1Acanthite
Ag
 
2
S
3.2.3Naumannite
Ag
 
2
Se
3.2.4Aguilarite
Ag
 
4
SeS
3.2.6Empressite
AgTe
3.2.7Stützite
Ag
 
5-x
Te
 
3
, x = 0.24-0.36
3.2.8Cervelleite
Ag
 
4
TeS
3.2.9Dervillite
Ag
 
2
AsS
 
2
3.2.10Stromeyerite
AgCuS
3.2.11Mckinstryite
Ag
 
5-x
Cu
 
3+x
S
 
4
3.2.12Jalpaite
Ag
 
3
CuS
 
2
3.2.13Eucairite
AgCuSe
3.2.14Cameronite
AgCu
 
7
Te
 
10
3.2.15Henryite
Ag
 
3
Cu
 
4
Te
 
4
3.2.16Sternbergite
AgFe
 
2
S
 
3
3.2.17Argentopyrite
AgFe
 
2
S
 
3
3.2.18Geffroyite
(Cu,Fe,Ag)
 
9
(Se,S)
 
8
3.2.19Argentopentlandite
Ag(Fe,Ni)
 
8
S
 
8

Other Names for Hessite

Synonyms:
BotesiteSavodinskiteTellursilberglanz
Other Languages:
Catalan:Hessita
Dutch:Hessiet
German:Botesit
Hessit
Savodinskit
Italian:Hessite
Russian:Гессит
Simplified Chinese:碲银矿
辉碲银矿
Spanish:Botesita
Hessita
Savodinskita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:Silver ore

References for Hessite

Reference List:

- +
Hillebrand, William Francis (1899), Mineralogical notes: melonite (?), coloradoite, petzite, hessite: American Journal of Science, 4th. series: 8: 295-298.

Borchert (1930) [on phase transition at 155°C]

Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged, 834pp.: 184-186.

Thompson, R.M. (1949) The telluride minerals and their occurrence in Canada. American Mineralogist: 34: 342-382.

Van der Lee, A. and J.L. de Boer (1959) Redetermination of the structure of hessite, Ag2Te-III. Acta Crystallographica: C49: 1444-1446.

Criddle, A.J. and C.J. Stanley, Eds., (1993) Quantitative data file for ore minerals, 3rd. edition. Chapman & Hall, London: 237.

Zeitschrift für Kristallographie: 112: 44-52.

Internet Links for Hessite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Hessite details from Handbook of Mineralogy (PDF)
  • Mineral Dealers:
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  • Specimens:The following Hessite specimens are currently listed for sale on minfind.com.

    Localities for Hessite

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