Editorial Feature

Arsenbrackebuschite – Occurrence, Properties, and Distribution

May 20 2014

Arsenbrackebuschite was named by Wolfgang Hofmeister and E. Tilmanns in 1976, in allusion to this species being an arsenate within the brackebuschite group. It belongs to the brackebuschite group.

Properties of Arsenbrackebuschite

The following are the key properties of arsenbrackebuschite:

Cell Data
- Space group: P2₁/m
- a = 7.763(1)
- b = 6.046(1)
- c = 9.022(1)
- β = 112.5(1)°
- Z = 2

Crystal Data
- Monoclinic
- Point group: 2/m
- As tiny flat plates or laths, to 0.5mm
- Very fine-grained, massive
- Twinning: Complex, observed
- X-ray powder pattern: 3.012 (100d), 3.268 (90), 2.777 (60), 2.313 (30), 2.133 (30), 4.92 (25), 3.68 (25)

Chemical Composition

Elements	Content 1
PbO	59.4
As₂O₅	30.5
Fe₂O₃	6.5
ZnO	3.1
P₂O₅	0.17
H₂O	n.d.
Total	99.67

Optical Properties
- Optical class: Biaxial (-)
- Pleochroism: Honey-yellow to bright yellow
- n = 2.0–2.1

Estimated Properties

Electron density	Bulk density (electron density) = 5.63 g/cm³ note: Specific gravity of arsenbrackebuschite = 6.54 g/cm³
Photoelectric	PE_{Arsenbrackebuschite} = 978.62 barns/electron U=PE_{Arsenbrackebuschite} x ρ electron density = 5,513.31 barns/cm³
Fermion index	Fermion index = 0.12 Boson index = 0.88
Radioactivity	Arsenbrackebuschite is not radioactive

How to Identify Arsenbrackebuschite

Arsenbrackebuschite can be identified in the field by its honey-yellow color. Its transparent to translucent form has {010} perfect cleavage. This mineral has an adamantine - resinous luster, with brownish-yellow streak.

The density of arsenbrackebuschite is 6.54 g/cm³, with a hardness of 4.5 -between fluorite and apatite.

Global Distribution

Arsenbrackebuschite is distributed in the following places:

Namibia - From Tsumeb
Austria - From Brixlegg, Tirol
Germany - In the Clara mine, near Oberwolfach, Black Forest
USA - At the Hornet mine, Hachita, Grant Co. New Mexico

Occurrence of Arsenbrackebuschite and Useful Mineral Association

Arsenbrackebuschite occurs in fissures in dolomite breccia, in the oxidized zone of a dolostone-hosted hydrothermal polymetallic ore deposit; and in a hydrothermal polymetallic barite–fluorite deposit.

It is often associated with minerals such as beudantite, mimetite, anglesite, bayldonite, and stolzite.