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About ChalcoditeHide

Golden yellow to yellow brown
Sub-Vitreous, Resinous, Pearly, Sub-Metallic
Specific Gravity:
Crystal System:
Named by Charles Upham Shepard in 1851 from the Greek, χαλκώδης, meaning "brass-like" in allusion to its appearance. Brush (1858) cast doubt on the uniqueness of chalcodite. Brush (1858) admitted to having too little of the mineral from the type locality to analyze, and instead analyzed a dissimilar mineral from a different locality (Natural Bridge, New York, USA). The Natural Bridge mineral was a pseudomorph after an unknown mineral. Brush concluded that the Antwerp, New York mineral, while dissimilar to the Natural Bridge mineral was not new. During the 1830s and 1840s, Shepard was embroiled in a family feud regarding Shepard's predilection of naming minerals based on the Mohs method of naming minerals and the feud extended through the mineral faculty at Yale University and chalcodite. See King (2012) and King and Nemetz (2013). Although Brush (1858) did not analyze similar material from the type locality, from the vantage point of time, his doubt was unfounded. Unlike the variety of stilpnomelane called ferristilpnomelane, chalcodite is the completely ferric analog of stilpnomelane, as originally analyzed by Shepard.
Dimorph of:
Radiating micaceous bronzey clusters.

Currently not approved by the IMA.

Classification of ChalcoditeHide

Published without approval

Physical Properties of ChalcoditeHide

Sub-Vitreous, Resinous, Pearly, Sub-Metallic
Transparent, Translucent
Sometimes said to be "bronzy".
Golden yellow to yellow brown
Yellow to greenish brown; also dark brown
Hardness Data:
2.76 g/cm3 (Measured)    

Optical Data of ChalcoditeHide

Biaxial (-)
RI values:
nα = 1.630 - 1.635 nγ = 1.740 - 1.760
Max Birefringence:
δ = 0.110 - 0.125
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
X = pale greenish yellow to colorless, Y = Z = deep grass green
~68 mole % ferric-dominant material, Cowcliff Hill, Western Otago, New Zealand (Hutton, 1945)

Chemical Properties of ChalcoditeHide


Crystallography of ChalcoditeHide

Crystal System:

First Recorded Occurrence of ChalcoditeHide

General Appearance of First Recorded Material:
Aggregates of golden yellow to golden brown open radial groups of micaceous plates.
Geological Setting of First Recorded Material:
Hematite-rich iron deposit
Associated Minerals at First Recorded Locality:

Relationship of Chalcodite to other SpeciesHide

Other Members of this group:
Franklinphilite(K,Na)4(Mn2+,Mg,Zn)48(Si,Al)72(O,OH)216 · 6H2OTric.
LennilenapeiteK6-7(Mg,Mn,Fe,Zn)48(Si,Al)72(O,OH)216 · 16H2OTric.
Parsettensite(K,Na,Ca)7.5(Mn,Mg)49Si72O168(OH)50 · nH2OMon. 2/m : B2/m
Stilpnomelane(K,Ca,Na)(Fe2+,Mg,Al)8(Si,Al)12(O,OH)36 · nH2OTric. 1 : P1

Common AssociatesHide

Associated Minerals Based on Photo Data:
4 photos of Chalcodite associated with HematiteFe2O3
1 photo of Chalcodite associated with Ferroan DolomiteCa(Mg,Fe)(CO3)2
1 photo of Chalcodite associated with MagnetiteFe2+Fe3+2O4

Fluorescence of ChalcoditeHide

Not fluorescent

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for ChalcoditeHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Shepard, C. U., 1852, Chalcodite, A Treatise on Mineralogy, third edition, B. L. Hamlin, New Haven, p. 153.
Brush, G. J. (1858) On Chalcodite. American Journal of Science, second series, 25, 198-201.
Dana, Edward S., 1892, The System of Mineralogy, sixth edition,, John Wiley & Sons, New York, p. 658.
Ferrier, Walter F. (1896) Erythrite, Stilpnomelane var. chalcodite; Crystallized Monazite; Pleochroic Apatite from Canadian Localities. The Ottawa Naturalist, 9 (10), 194.
Shannon, Earl V. (1920) Diabantite, stilpnomelane, and chalcodite of the trap quarries of Westfield, Massachusetts, Proceedings of the United States National Museum, 57, 397-403.
Hutton, C. Osborne, 1945, Additional Optical and Chemical Data on the Stilpnomelane Group of Minerals. American Mineralogist 30, 714-718.
Hutton, C. Osborne, 1945, Further Data on the Stilpnomelane Mineral Group. American Mineralogist 41, 608-615.
Winchell, Alexander N. and Winchell, Horace, 1951, Optical Mineralogy, fourth edition, part 2, p. 390.
Eggleton, Richard A. and Bailey, Sturgis W. (1971) The Crystal Structure of Stilpnomelane Part I. The Subcell, Clays and Clay Minerals, 13, 49.
Deer, W. A., Howie, R. A., and Zussman, J., 1971, Stilpnomelane,Rock-Forming Minerals, volume 3 Sheet Silicates p. 103-114.
Eggleton, Richard A. and Bailey, Sturgis W. (1971) The Crystal Structure of Stilpnomelane Part I. The Full Cell, Mineralogical Magazine, 38, 693-711.
Eggleton, Richard A. and Chappell, B. W. (1971) The Crystal Structure of Stilpnomelane III. Chemistry and Physical Properties, Mineralogical Magazine, 42, 361-368.
Chauvel, Jean-Jacques (1973) Les Stilpnomelanes. Proprieties physiques et composition chimique, Contribution of Mineralogy and Petrology, 38, 37-44.
Brindley, George W. and de Souza, Jefferson Veira (1975) A Goldencolored, Ferri-Nickel Chloritic Mineral from Morro do Niquel, Minas Gerais, Brazil, Clays and Clay Minerals, 23, 11-15.
King, Vandall T. (2012) In Search of Why Charles Upham Shepard's Minerals did not Survive the Test of Time, Program and Abstracts 39th Rochester Mineralogical Symposium, p. 37-38.
King, Vandall T. and Nemetz, Janet D. (2013) Eumanite - Further Suggestion of a Silliman-Dana-Shepard Family Feud, Program and Abstracts 40th Rochester Mineralogical Symposium, p. 17-18.

Internet Links for ChalcoditeHide

Localities for ChalcoditeHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • Ontario
    • Hastings Co.
      • Madoc Area
Van King
        • Madoc Township
Richard Gunter Collection
  • Québec
    • Chaudière-Appalaches
      • Les Appalaches RCM
        • Saint-Pierre-de-Broughton (West Broughton)
New Zealand
  • Otago Region
    • Queenstown-Lakes District
      • Queenstown
Hutton, C. Osborne, 1945, Further Data on the Stilpnomelane Mineral Group,American Mineralogist v.41 p. 608-615.
  • Aust-Agder
    • Evje og Hornnes
D. Cericola photo
  • Valais
    • Martigny
Alpinisme et Mineraux
  • California
    • Santa Clara Co.
      • San Jose
        • Oak Hill
Hutton, C. Osborne, 1945, Further Data on the Stilpnomelane Mineral Group,American Mineralogist v.41 p. 608-615.
  • Colorado
    • San Juan Co.
Rob Lavinsky photo
  • Connecticut
    • Hartford Co.
      • East Granby
R. Zinderman photo
  • Maine
    • Somerset Co.
Charles Guidotti, personal communication, 1991; King and Foord (1994) Mineralogy of Maine, vol. 1, p. 338
  • Massachusetts
    • Hampden Co.
      • Westfield
Shannon, Earl V., 1921, Diabantite, Stilpnomelane, and Chalcodite of the Trap Quarries of Westfield, Massachusetts, Proceedings of the United States National Museum, v. 57, 397-403.
  • New Hampshire
    • Carroll Co.
      • Conway
Peter Cristophano photo
  • New Jersey
    • Hudson Co.
      • Secaucus
Nick Faciollo
    • Sussex Co.
      • Franklin Mining District
        • Franklin
Clifford Frondel, Harvard University specimen
  • New York
    • Jefferson Co.
      • Antwerp
Shepard, Charles U., 1852, Chalcodite, A Treatise on Mineralogy, third edition, B. L. Hamlin, New Haven, p. 153.
  • Pennsylvania
    • Chester Co.
      • Warwick Township
        • St. Peters
Edith Trybalski
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