Editorial Feature

Apachite - Occurrence, Properties, and Distribution

Sep 26 2013

Apachite is a copper silicate mineral first discovered from Christmas Mine, Gila, Arizona, USA in 1979. The mineral was named for the Apache Indians, whose reservation is near the locality.

Properties of Apachite

The following are the key properties of Apachite:

Cell Data
- Space Group: n.d
- a = 12.89
- b = 6.055
- c = 19.11
- β = 90:42°
- Z = [2]
Crystal Data
- Monoclinic
- Point Group: n.d
- As minute, twisted or curved beaded spherules of radial fibers, composed of crystals; in seams, exhibiting a silky, fibrous structure on broken surfaces
- X-ray Powder Pattern: 12.89 (100), 3.168 (70), 7.663 (50), 10.62 (40), 9.556 (40), 4.491 (40), 4.174 (40).

Chemical Composition

Elements	Content 1	Content 2
CuO	43.6	47.26
SiO₂	40.8	39.66
H₂O	13.8	13.08
CaO	1.8	-
MgO	1.7	-
FeO	0.3	-
Total	102	100

Optical Properties
- Optical Class: Biaxial (-)
- Orientation: Y ≃ length
- α = 1.610
- β = 1.650
- γ = 1.650
- 2V(meas.) = Small.

Estimated Properties

Electron density	Bulk density (electron density) = 3.31 g/cm³ note: Specific gravity of Apachite = 3.37 g/cm³
Photoelectric	PE_Apachite = 16.97 barns/electron U = PE_Apachite x ρ Electron density = 56.11 barns/cm³
Fermion index	Fermion index = 0.008 Boson index = 0.99
Radioactivity	Apachite is not radioactive.

How to Identify Apachite

Apachite is a translucent blue-colored mineral with a light blue streak. The mineral exists as spherical, rounded aggregates or radial crystals. The average density of apachite is 2.8 g/cm³, and this mineral has a hardness of 2.

Global Distribution

Apachite is widely distributed in Christmas copper mine, Gila Co., Arizona, USA.

Occurrence of Apachite and Useful Mineral Association

Apachite occurs as a retrograde metamorphic or mesogene mineral formed at the expense of a prograde calc-silicate in tactites. It can also be observed in fractures or crackled zones cutting garnet-diopside rock, replacing both these silicates and calcite. The mineral is closely associated with tobermorite, calcite, apophyllite, xonotlite, clinohedrite, junitoite, stringhamite, gilalite and kinoite.