Editorial Feature

Andorite – Occurrence, Properties, and Distribution

May 12 2014

Andorite is named after Andor von Semsey (1833–1923), a Hungarian nobleman who was also an amateur mineralogist. It is a sulfosalt mineral that belongs to the ramdohrite-lillianite group.

Properties of Andorite

The following are the key properties of andorite:

Cell Data
- Space group: Pmma
- a = 13.01
- b = 19.19
- c = 4.27
- Z = [4]

Crystal Data
- Orthorhombic
- Point group: 2/m2/m2/m
- Stout prismatic, to 3cm; also thick and thin tabular on {100}, striated k [001]; massive
- Twinning: Reported on {110}
- X-ray powder pattern: 3.30 (100), 2.90 (80), 3.45 (40), 2.76 (40), 3.74 (30), 2.06 (30), 1.888 (30)

Chemical Composition

Elements	Content 1	Content 2	Content 3
Sb	41.31	40.75	41.87
Pb	24.10	22.25	23.75
S	22.06	24.26	22.02
Ag	10.94	10.90	12.36
Cu	0.68	0.96	-
Zn	-	0.31
Fe	0.30	0.75	-
Total	99.39	100.18	100.00

Optical Properties
- R1–R2: (400) 38.8–41.8, (420) 38.6–42.0, (440) 38.4–42.2, (460) 37.9–42.2, (480) 37.5–42.1, (500) 37.1–41.9, (520) 36.7–41.5, (540) 36.4–41.2, (560) 36.1–40.8, (580) 35.8–40.4, (600) 35.5–39.9, (620) 35.3–39.5, (640) 35.0–39.1, (660) 34.7–38.6, (680) 34.3–38.1, (700) 33.9–37.6

Estimated Properties

Electron density	Bulk density (electron density) = 4.71 g/cm³ note: Specific gravity of andorite = 5.44 g/cm³
Photoelectric	PE_Andorite = 596.64 barns/electron U=PE_Andorite x ρ electron density= 2,811.66 barns/cm³
Fermion index	Fermion index = 0.05 Boson index = 0.95
Radioactivity	Andorite is not radioactive

How to Identify Andorite

Andorite can be identified in the field by its color variations, such as grayish-yellow, dark gray, and steel gray. Its opaque form has no cleavage. This mineral has a metallic luster, with black streak. The fracture on this mineral is conchoidal. The density of andorite is 5.33 - 5.37 g/cm³, with a hardness of 3.5.

Global Distribution

Andorite is distributed in the following places:

Romania - From Baia Sprie (Felsobanya) [TL]
Czech Republic - At Trebsko, near Pribram
France - From Les Farges mine, near Ussel, Correze; and at Bournac, Montagne Noire, Finistere
Slovakia - In the Zlata Bana deposit, Slanske vrchy Mountains
Canada - From near Takla Lake, British Columbia, and near Nansen Creek, Yukon Territory
USA - At the Keyser and Morey mines, Morey district, Nye Co. Nevada; in the Thompson mine, Darwin district, Inyo Co. California; and at Bear basin, King Co. Washington
Australia - From the Meerschaum mine, north of Omeo, Victoria
Bolivia - In the Itos and San Jos´e mines, Oruro; at the Tatasi mine, and Cerro Rico, Potosi.

Occurrence of Andorite and Useful Mineral Association

Andorite occurs in low-temperature polymetallic hydrothermal veins.

It is often associated with minerals such as stibnite, sphalerite, barite, fluorite, siderite, quartz, cassiterite, arsenopyrite, stannite, zinkenite, tetrahedrite, pyrite, alunite, pyrargyrite, stephanite, and rhodochrosite.