Hjelmite
A discredited species name
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About Hjelmite
Colour:
Black
Lustre:
Metallic
Hardness:
5
Specific Gravity:
5.2 - 5.8
Name:
After the Swedish chemist P.J. Hjelm (1746-1813). Named and described by Nordenskiöld (1860) from Kårarvet, Falun, Sweden. However, on the basis of the morphological data, he considered it to be a dubious species, related to tapiolite and samarskite. Crook (1979) investigated a sample labelled as hjelmite from Kårarvet, and found it to be the tantalum equivalent of yttropyrochlore, and named it yttromicrolite. Reinvestigation of co-type found Crook's analysis to be in error and concluded that the type "yttromicrolite" is an amorphous mixture of calcium sulfate, tantalite and heterogeneous microlite (Peacor et al., 1982).
An inadequately described/studied oxide or niobate-tantalate containing Y, Fe2+, U4+, Sn, Mn, Ca, Nb, Ta.
Hjelmite was first described from Kårarvet Mine near Falun, Sweden by Nordenskiöld (1860) who considered it, on the basis of morphological data, to be a dubious species, possibly related to tapiolite or samarskite. It may be yttromicrolite-(Y).
Hjelmite was first described from Kårarvet Mine near Falun, Sweden by Nordenskiöld (1860) who considered it, on the basis of morphological data, to be a dubious species, possibly related to tapiolite or samarskite. It may be yttromicrolite-(Y).
Unique Identifiers
Mindat ID:
30172
Long-form identifier:
mindat:1:1:30172:9
IMA Classification of Hjelmite
Discredited, Questionable
Approval history:
Discredited by IMA in 1979 and renamed ytttromicrolite. Discredited again in 1982.
Physical Properties of Hjelmite
Metallic
Colour:
Black
Streak:
Grayish black
Hardness:
5 on Mohs scale
Fracture:
Irregular/Uneven
Density:
5.2 - 5.8 g/cm3 (Measured)
Optical Data of Hjelmite
Crystallography of Hjelmite
Morphology:
Rough and indistinct crystals. Massive; rounded or prismatic aggregates.
Synonyms of Hjelmite
Other Information
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 Hjelmite
mindat.org URL:
https://www.mindat.org/min-30172.html
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References for Hjelmite
Localities for Hjelmite
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.
Sweden | |
| Nordenskjöld (1860) |
| Wilke (1997) |
Norberg, Västmanland County, Sweden