Gabrielite

Formula:

(As,Sb)

System:

Triclinic

Colour:

grey to black

Hardness:

1½ - 2

Name:

Named for Walter Gabriel of Basel, Switzerland, well-known mineral photographer and expert of the Lengenbach minerals

This page provides mineralogical data about Gabrielite.

Classification of Gabrielite

IMA status:

Approved 2002

Strunz 8th edition ID:

2/E.14-

Nickel-Strunz 10th (pending) edition ID:

2.HD.60

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

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Type Occurrence of Gabrielite

Type Locality:

Lengenbach Quarry, Im Feld (Imfeld; Feld; Fäld), Binn Valley, Wallis (Valais), Switzerland

General Appearance of Type Material:

idiomorphic short-prismatic to platy crystals up to approximately 0.4 mm, and aggregates to about 1 mm across

Geological Setting of type material:

arsenic-rich sulphide mineralization in triassic dolomite

Associated Minerals at type locality:

Trechmannite	Tennantite	Realgar	Rathite	Hutchinsonite
Hatchite	Edenharterite

Physical Properties of Gabrielite

Lustre:

Metallic

Diaphaneity (Transparency):

Opaque

Colour:

grey to black

Streak:

blackish red

Hardness (Mohs):

1½ - 2

Hardness (Vickers):

VHN₁₀=18 kg/mm²

Cleavage:

Perfect
along (001)

Density (calculated):

5.38 g/cm³

Crystallography of Gabrielite

Crystal System:

Triclinic

Class (H-M):

1 - Pedial

Space Group:

Cell Parameters:

a = 12.138Å, b = 12.196Å, c = 15.944Å
α = 78.537°, β = 84.715°, γ = 60.47°

Ratio:

a:b:c = 0.995 : 1 : 1.307

Unit Cell Volume:

V 2013 Å³

Morphology:

pseudohexagonal crystals, short prismatic to platy parallel to (001)

Twinning:

common, with (100) as twin plane

X-Ray Powder Diffraction:

d-spacing		Intensity
15.63		(100)
3.143		(90)
3.531		(80)
2.911		(70)
2.520		(60)

Comments:

Format: dobs/Å (Iobs/%) (hkl)

Optical Data of Gabrielite

Type:

Anisotropic

Anisotropism:

weak

Reflectivity:

470nm	R=30.53%
546nm	R=29.1%
589nm	R=27.94%
650nm	R=26.35%

Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 30.53%.

Colour in reflected light:

white

Internal Reflections:

red

Chemical Properties of Gabrielite

Formula:

(As,Sb)

Idealised Formula:

AgCu

All elements listed in formula:

Ag, As, Cu, S, Sb, Tl

Analytical Data:

Mean values out of 11 electron microprobe analyses

Tl (37.30)
Cu (12.50)
Ag (8.47)
As (18.90)
Sb (1.79)
S (20.64)

sum 99.70 wt%

Empirical Formula:

5.95

2.56

6.46

9.02

8.23

0.48

Relationship of Gabrielite to other Species

2.HD.05

Lorándite

TlAsS

2.HD.05

Weissbergite

TlSbS

2.HD.15

Christite

TlHgAsS

2.HD.20

Jankovićite

(As,Sb)

2.HD.20

Jankovicite

2.HD.25

Rebulite

2.HD.30

Imhofite

CuAs

2.HD.35

Edenharterite

PbTlAs

2.HD.40

Jentschite

TlPbAs

SbS

2.HD.45

Hutchinsonite

(Tl,Pb)

2.HD.50

Bernardite

Tl(As,Sb)

2.HD.55

Sicherite

TlAg

(As,Sb)

Other Names for Gabrielite

Synonyms:

IMA2002-053

Other Languages:

German:	Gabrielit
Russian:	Габриелит

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.

References for Gabrielite

Reference List:

Graeser, S., Topa, D., Balić-Žunić, T., Makovicky, E. (2006): Gabrielite, Tl2AgCu2As3S7, a new species of thallium sulfosalt from Lengenbach, Binntal, Switzerland. Canadian Mineralogist: 44: 135-140.

Balić-Žunić, T., Makovicky, E., Karanović, L., Poleti, D., Graeser, S. (2006): The crystal structure of gabrielite, Tl2AgCu2As3S7, a new species of thallium sulfosalt from Lengenbach, Switzerland. Canadian Mineralogist: 44: 141-158.