Erdite
A valid IMA mineral species
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About Erdite
R. Erd, G. Foord and E. Oyler
Formula:
NaFeS2 · 2H2O
Colour:
Copper-red
Lustre:
Metallic
Hardness:
2
Specific Gravity:
2.30
Crystal System:
Monoclinic
Name:
Named by G.K. Czamanske, B.F. Leonard, J.R. Clark in 1980 in honor of Richard Clarkson "Dick" Erd (29 February 1924, Lexington, Kentucky, USA - 20 May 2008, Springdale, Arkansas, USA), mineralogist with the US Geological Survey. He had previously synthesized the substance in 1956.
Type Locality:
This page provides mineralogical data about Erdite.
Unique Identifiers
Mindat ID:
1394
Long-form identifier:
mindat:1:1:1394:5
Similar Names
| Ernite | A synonym of Grossular | |
| Errite | A synonym of Parsettensite | |
| Ordite | A variety of Gypsum | CaSO4 · 2H2O |
| Urdite | A synonym of Monazite Group | |
| Verdite | A variety of 'Fuchsite' [Muscovite] | KAl2(AlSi3O10)(OH)2 |
IMA Classification of Erdite
Classification of Erdite
2.FD.20
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
F : Sulfides of arsenic, alkalies; sulfides with halide, oxide, hydroxide, H2O
D : With O, OH, H2O
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
F : Sulfides of arsenic, alkalies; sulfides with halide, oxide, hydroxide, H2O
D : With O, OH, H2O
Dana 7th ed.:
2.14.5.1
2.14.5.1
2 : SULFIDES
14 : Hydroxysulfides and Hydrated Sulfides
2 : SULFIDES
14 : Hydroxysulfides and Hydrated Sulfides
3.0.1
3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
0 : Sulphides etc. of the alkalis
3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
0 : Sulphides etc. of the alkalis
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Erd | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Erdite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Erdite
Metallic
Transparency:
Opaque
Colour:
Copper-red
Comment:
Tarnishes quickly
Streak:
Black
Hardness:
2 on Mohs scale
Hardness:
VHN15=22 - 67 kg/mm2 - Vickers
Cleavage:
Distinct/Good
{110} Good
{110} Good
Density:
2.30 g/cm3 (Measured) 2.216 g/cm3 (Calculated)
Comment:
Measured contaminated with magnetite
Optical Data of Erdite
Anisotropism:
Strong.
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 400nm | 10.2% | 23.8% |
| 420nm | 9.8% | 28.8% |
| 440nm | 10.1% | 27.3% |
| 460nm | 10.9% | 20.8% |
| 480nm | 11.3% | 15.6% |
| 500nm | 11.3% | 16.6% |
| 520nm | 11.0% | 23.3% |
| 540nm | 10.6% | 25.7% |
| 560nm | 10.3% | 25.7% |
| 580nm | 10.0% | 31.6% |
| 600nm | 9.8% | 36.6% |
| 620nm | 9.7% | 43.1% |
| 640nm | 9.8% | 46.9% |
| 660nm | 10.0% | 44.3% |
| 680nm | 10.6% | 39.3% |
| 700nm | 11.0% | 35.3% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 46.9%.
R1 shown in black, R2 shown in red
Pleochroism:
Strong
Comments:
Extreme. Brilliant reddish-orange through greenish grays and pinkish grays to dark gray with barely perceptible bluish or greenish tint.
Chemistry of Erdite
Mindat Formula:
NaFeS2 · 2H2O
Element Weights:
Common Impurities:
K
Crystallography of Erdite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Setting:
C2/c
Cell Parameters:
a = 10.693 Å, b = 9.115 Å, c = 5.507 Å
β = 92.17°
β = 92.17°
Ratio:
a:b:c = 1.173 : 1 : 0.604
Unit Cell V:
536.36 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Minute fibers, fine bladed crystals to 1 mm long.
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0000785 | Erdite | Konnert J A, Evans H T (1980) The crystal structure of erdite, NaFeS2*2H2O American Mineralogist 65 516-521 |  | 1980 | Coyote Peak, Humboldt County, California, USA | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.935 Å | (100) |
| 5.342 Å | (71) |
| 4.556 Å | (41) |
| 3.467 Å | (28) |
| 2.310 Å | (23) |
| 2.902 Å | (15) |
| 3.317 Å | (12) |
Comments:
Coyote Peak, California, USA.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4a: Earth’s earliest continental crust | >4.4-3.0 |
| 19 : Granitic intrusive rocks | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] |
Geological Setting:
Pegmatites in nepheline syenite
Type Occurrence of Erdite
General Appearance of Type Material:
Copper-red granular masses of impure erdite reach dimensions of several millimeters. The largest clean single crystals measure 0.5 x 1 mm.
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA.
Geological Setting of Type Material:
In mafic, alkalic diatreme. Very young rock (29 m.y.)
Associated Minerals at Type Locality:
Synonyms of Erdite
Other Language Names for Erdite
Common Associates
Associations Based on Photo Data:
| 17 photos of Erdite associated with Martinite | (Na,◻,Ca)12Ca4(Si,S,B)14B2O38(OH,Cl)2F2 · 4H2O |
| 7 photos of Erdite associated with 'Hackmanite' | Na8Al6Si6O24Cl2 |
| 5 photos of Erdite associated with Phlogopite | KMg3(AlSi3O10)(OH)2 |
| 5 photos of Erdite associated with Nepheline | Na3K(Al4Si4O16) |
| 5 photos of Erdite associated with Aegirine | NaFe3+Si2O6 |
| 3 photos of Erdite associated with Schorlomite | Ca3Ti2(SiO4)(Fe3+O4)2 |
| 2 photos of Erdite associated with Coyoteite | NaFe3S5 · 2H2O |
| 2 photos of Erdite associated with Rasvumite | KFe2S3 |
| 1 photo of Erdite associated with Pyrrhotite | Fe1-xS |
| 1 photo of Erdite associated with 'Unnamed (MSH UK-86)' | Fe, S, Si, O, Na, K, Cl |
Related Minerals - Strunz-mindat Grouping
| 2.FD. | Ferrovalleriite | 2(Fe,Cu)S · 1.5Fe(OH)2 |
| 2.FD.05 | Kermesite | Sb2S2O |
| 2.FD.10 | Viaeneite | (Fe,Pb)4S8O |
| 2.FD.25 | Coyoteite | NaFe3S5 · 2H2O |
| 2.FD.30 | Yushkinite | (Mg,Al)V4+S2(OH)2 |
| 2.FD.30 | Valleriite | (Fe2+,Cu)4(Mg,Al)3S4(OH,O)6 |
| 2.FD.30 | Ekplexite | (Nb,Mo,W)S2 · (Mg1-xAlx)(OH)2+x |
| 2.FD.30 | Haapalaite | (Fe2+,Ni)2(Mg,Fe2+)1.61S2(OH)3.22 |
| 2.FD.35 | Kaskasite | (Mo,Nb)S2 · (Mg1-xAlx)(OH)2+x |
| 2.FD.35 | Manganokaskasite | (Mo,Nb)S2 · (Mn1-xAlx)(OH)2+x |
| 2.FD.35 | Tochilinite | Fe2+5-6(Mg,Fe2+)5S6(OH)10 |
| 2.FD.35 | Ferrotochilinite | Fe2+6(Fe2+,Mg)5S6(OH)10 |
| 2.FD.40 | Wilhelmramsayite | Cu3FeS3 · 2H2O |
| 2.FD.45 | Vyalsovite | FeCaAlS(OH)5 |
| 2.FD.50 | Bazhenovite | Ca8S2(S3)(S2O3)(OH)12 · 20H2O |
| 2.FD.55 | 'UM2004-56-OS:BiCuPb' | PbCu4Bi4S2(O,OH,H2O)16 (?) |
Other Information
Thermal Behaviour:
When heated in a closed tube, it gives off water, sulfur and eventually turns black and strongly magnetic.
Notes:
Easily soluble in cold dilute acids with effervescence of H2S.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Erdite
mindat.org URL:
https://www.mindat.org/min-1394.html
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References for Erdite
Localities for Erdite
Showing 8 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Canada | |
| Horváth et al. (1990) +1 other reference |
| Horváth et al. (1998) |
| Horváth et al. (1998) | |
Ghana | |
| Addae et al. (2026) |
Oman | |
| Pracejus et al. (2022) |
Poland | |
| Cu +2 other references |
Russia | |
| [World of Stones 95:5-6 |
USA (TL) | |
| Czamanske et al. (1980) +4 other references |
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Coyote Peak, Humboldt County, California, USA