Jun 5 2014
Erdite is a monoclinic-prismatic mineral, composed of sulfur, sodium, oxygen, iron, and hydrogen. It was first discovered in 1977 from the Coyote Peak diatreme, 16 miles south-west of Orick, Humboldt Co. California.
It was named after Dr. Richard Clarkson Erd, an American mineralogist with the U.S. Geological Survey, who first discovered it.
Properties of Erdite
The following are the key properties of Erdite:
- Cell Data
- Space Group: C2/c
- a = 10.677–10.693
- b = 9.083–9.115
- c = 5.499–5.507
- β = 92°10(2)'-92°23(4)'
- Z = 4
- Crystal Data
- Monoclinic
- Point Group: 2/m
- In fine granular, impure masses of minute fibers; single, fine-bladed crystals, to 1mm in length
- X-ray Powder Pattern: 6.935 (100), 5.342 (71), 4.556 (41), 3.467 (28), 2.310 (23), 2.902 (15), 3.317 (12)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
Content 3 |
| S |
40.5 |
37.6 |
35.82 |
| Fe |
36.0 |
34.9 |
31.20 |
| Na |
14.1 |
11.2 |
12.84 |
| O |
[9.4] |
[16.2] |
17.88 |
| K |
- |
0.12 |
- |
| H |
- |
- |
[2.26] |
| Total |
[100.0] |
[100.02] |
100.00 |
- Optical Properties
- Pleochroism: Extreme: brilliant reddish-orange through greenish-grays and pinkish-grays, to dark gray with a barely perceptible bluish or greenish tint
- Anisotropism: Strong
- Estimated Properties
| Electron density |
Bulk density (electron density) = 2.21 g/cm3
note: Specific gravity of Erdite = 2.22 g/cm3 |
| Photoelectric |
PEErdite = 11.26 barns/electron
U = PEErdite x ρElectron density = 24.86 barns/cm3 |
| Fermion index |
Fermion index = 0.009
Boson index = 0.99 |
Radioactivity
|
Erdite is not radioactive
|
How to Identify Erdite
Erdite can be identified in the field by a range of colors, from red to copper-red and black. It has a good cleavage, metallic luster, and black streak.
The density of erdite is 2.3 g/cm3, and its hardness is 2.
Global Distribution
Erdite is distributed in the following places:
- Mont Saint-Hilaire and near Saint-Amable, Quebec, Canada
- Mt. Alluaiv, Lovozero massif, Kola Peninsula, Russia
- Coyote Peak, near Orick, Humboldt Co. California, USA
Occurrence of Erdite and Useful Mineral Association
Erdite occurs in late segregations within an alkalic mafic diatreme, and pegmatites in nepheline syenite.
Minerals such as murmanite, pyrite, bartonite, djerfisherite, rasvumite, magnetite, and pyrrhotite are all closely related to erdite.
References