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Bernardite

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Formula:
TlAs5S8
System:
Monoclinic
Colour:
Black
Lustre:
Dull
Hardness:
2
Name:
In honor of Jan H. Bernard (1928-), Czech mineralogist, Professor of Geochemistry at Charles University, Prague (1955-1967) and Central Geological Institute (Prague). He is the author or co-author of numerous publications including Mineralogy of Czechoslovakia (1969 & 1981), Minerals and their localities (2004).
This page provides mineralogical data about Bernardite.


Classification of Bernardite

Approved
Approval Year:
1987
2.HD.50

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
H : Sulfosalts of SnS archetype
D : With Tl
3.8.14.2

3 : SULFOSALTS
8 : 1 < ø < 2
5.5.9

5 : Sulphosalts - Sulpharsenites and Sulphobismuthites (those containing Sn, Ge,or V are in Section 6)
5 : Sulpharsenites etc. of Tl

Physical Properties of Bernardite

Diaphaneity (Transparency):
Translucent
Colour:
Black
Streak:
Red
Hardness (Mohs):
2
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
4.5 g/cm3 (Measured)    4.105 g/cm3 (Calculated)

Optical Data of Bernardite

Type:
Anisotropic
Reflectivity:
400nmR1=29.6%R2= 32.3%
420nmR1=28.9%R2= 31.8%
440nmR1=28.1%R2= 31.3%
460nmR1=27.4%R2= 30.6%
480nmR1=26.8%R2= 29.9%
500nmR1=26.0%R2= 28.9%
520nmR1=25.4%R2= 27.8%
540nmR1=25.0%R2= 26.7%
560nmR1=24.5%R2= 25.8%
580nmR1=24.0%R2= 25.1%
600nmR1=23.6%R2= 24.4%
620nmR1=23.3%R2= 23.9%
640nmR1=23.1%R2= 23.4%
660nmR1=22.9%R2= 23.0%
680nmR1=22.8%R2= 22.8%
700nmR1=22.8%R2= 22.5%

Reflectance graph
Graph shows reflectance levels at different wavelengths (in nm). Top of box is 100%. Peak reflectance is 32.3%.
R1 shown in black, R2 shown in red

Chemical Properties of Bernardite

Formula:
TlAs5S8

Some As may be replaced by Sb.
Elements listed in formula:
Analytical Data:
Alšar, Macedonia; by electron microprobe
Tl (23.3)
As (43.7)
Sb (0.1)
S (31.5)
Total (98.6)

Crystallography of Bernardite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Space Group Setting:
P21/c
Cell Parameters:
a = 15.647(4) Å, b = 8.038(3) Å, c = 10.750(3) Å
β = 91.27(3)°
Ratio:
a:b:c = 1.947 : 1 : 1.337
Unit Cell Volume:
V 1,351.70 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Tabular crystals with prominent {100}, {012}, {210}, and {201}, {201}, {010}.
X-Ray Powder Diffraction Data:
d-spacingIntensity
4.46 (65)
4.28 (74)
3.72 (55)
3.68 (63)
3.07 (65)
3.06 (100)
2.68 (59)
Comments:
Calculated.

Occurrences of Bernardite

Type Occurrence of Bernardite

Empirical Formula:
Tl0.93(As4.75Sb0.01)S8.00

Relationship of Bernardite to other Species

2.HD.05LoránditeTlAsS2
2.HD.05WeissbergiteTlSbS2
2.HD.15ChristiteTlHgAsS3
2.HD.20JankovićiteTl5Sb9(As,Sb)4S22
2.HD.25RebuliteTl5Sb5As8S22
2.HD.30ImhofiteTl5.8As15.4S26
2.HD.35EdenharteriteTlPbAs3S6
2.HD.40JentschiteTlPbAs2SbS6
2.HD.45HutchinsoniteTlPbAs5S9
2.HD.55SicheriteTlAg2(As,Sb)3S6
2.HD.60GabrieliteTl2AgCu2As3S7
5.5.1LoránditeTlAsS2
5.5.2EllisiteTl3AsS3
5.5.3ImhofiteTl5.8As15.4S26
5.5.4SimoniteTlHgAs3S6
5.5.6ChristiteTlHgAsS3
5.5.6RouthieriteCuTlHg2As2S6
5.5.7HutchinsoniteTlPbAs5S9
5.5.8WallisiteCuPbTlAs2S5
5.5.10VrbaiteHg3Tl4As8Sb2S20
5.5.11RebuliteTl5Sb5As8S22
5.5.12GillulyiteTl2As7.5Sb0.3S13
5.5.13WeissbergiteTlSbS2
5.5.14Rohaite(Tl,Pb,K)2Cu8.7Sb2S4
5.5.15VaughaniteTlHgSb4S7
5.5.16Chalcothallite(Cu,Fe,Ag)6.3(Tl,K)2SbS4
5.5.17PierrotiteTlSb3As2S8
5.5.18ParapierrotiteTlSb5S8
5.5.19CriddleiteAg2Au3TlSb10S10
5.5.20ChabournéiteTl4Pb2(Sb,As)20S34

Other Names for Bernardite

Name in Other Languages:
German:Bernardit
Simplified Chinese:贝硫砷铊矿
Spanish:Bernardita

Other Information

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

References for Bernardite

Reference List:
American Mineralogist: 75: 1209.

Pašava, J., Pertlik, F., Stumpfl, E.F. and Zemann, J. (1989): Bernardite, a new thallium arsenic sulphosalt from Allchar, Macedonia, with a determination of the crystal structure. Mineralogical Magazine, 53, 531-538.

Internet Links for Bernardite

mindat.org URL:
https://www.mindat.org/min-636.html
Please feel free to link to this page.

Localities for Bernardite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
Republic of Macedonia (TL)
 
  • Rožden (Rozhden; Roszdan)
Pasava, J., Pertlik, F., Stumpfl, E. F., & Zemann, J. (1989). Bernardite, a new thallium arsenic sulphosalt from Allchar, Macedonia, with a determination of the crystal structure. Mineralogical Magazine, 53, 531-538. ; The Canadian Mineralogist Vol.32, pp. 649-665 (1994); Boevl, B., Bermanec, V., Serafimovski, T., Lepitkoval, S., & Mikulcic, S. (2001). Allchar Mineral Assemblage. Geologica Macedonica, Vol. 15-16, p. 1-23 (2001-2002) Suppl
Gunnar Farber specimens
Switzerland
 
  • Wallis (Valais)
    • Binn Valley
      • Fäld (Imfeld; Im Feld; Feld)
Graeser, S. & Edenharter, A. (1997): Jentschite (TlPbAs2SbS6) - a new sulfosalt mineral from Lengenbach, Binntal (Switzerland). Mineralogical Magazine 61, 131-137.; Graeser, St., Schwander, H., Wulf, R. & Edenharter, A. (1992): Erniggliite (Tl2SnAs2S6), a new mineral from Lengenbach, Binntal (Switzerland): description and crystal structure determination based on data from synchrotron radiation. Schweiz. Mineral. Petrogr. Mitt., 72, 293-305.; Graeser, S., Schwander, H., Wulf, R. (1995): Stalderite TlCu(Zn,Fe,Hg)2As2S6 - a new mineral related to routhierite: description and crystal structure determination. Schweizerische mineralogische und petrographische Mitteilungen 75, 337-345; Roth, P. (2016): Zwillinge seltener Lengenbach-Mineralien. Schweizer Strahler 50(2), 28-29 (in German and French).
Mineral and/or Locality  
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