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About ŠtěpiteHide

Josef Štěp
U(AsO3OH)2 · 4H2O
Emerald green
Specific Gravity:
3.90 (Calculated)
Crystal System:
Named in honour of Josef Štěp (1863-1926), head of the State mines in Jáchymov (1889-1924), who has published with F. Becke in 1904 a study on the occurrence of uranium ores at Jáchymov, and the "father" of the famous Jáchymov radon spa.
Second purely U4+ arsenate mineral after vysokýite. The other U-bearing hydroxyarsanate minerals are chadwickite and 'UM1958-05-AsO:HU', however, both contain U6+ instead of U4+.

The crystal structure is based on sheets of with [8]U and hydroxyarsenate "tetrahedra" perpendicular to [001]; 2/6 oxygens surrounding U atoms belong to the hydroxyarsenate groups, with remaining two oxygens belonging to interlayer water molecules. The UO8 polyhedra are linked to five other U polyhedra via six hydroxyarsenate groups. The [U(AsO3OH)2]0 sheets are linked by hydrogen bonds, that involve interlayer water molecules and sheet-residing OH groups.

Classification of ŠtěpiteHide

Approval Year:
First Published:

Physical Properties of ŠtěpiteHide

Emerald green
Gray to greenish gray
ca. 2
Very Good
3.90 g/cm3 (Calculated)
density couldn't be measured

Optical Data of ŠtěpiteHide

Biaxial (-)
RI values:
nα = 1.636(2) nβ = 1.667(3) nγ = 1.672(2)
Measured: 5° , Calculated: 43°
Max Birefringence:
δ = 0.036
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
2V(meas.) or β possibly incorrect
anomalous interference - grayish to pale yellow - on the (001) plane

Chemical Properties of ŠtěpiteHide

U(AsO3OH)2 · 4H2O
IMA Formula:
U(AsO3OH)2 · 4H2O
Common Impurities:

Crystallography of ŠtěpiteHide

Crystal System:
Class (H-M):
4/mmm (4/m 2/m 2/m) - Ditetragonal Dipyramidal
Space Group:
Cell Parameters:
a = 10.9894(1) Å, c = 32.9109(6) Å
a:c = 1 : 2.995
Unit Cell V:
3959.7 ų

X-Ray Powder DiffractionHide

Powder Diffraction Data:
8.190 Å(100)
7.008 Å(43)
5.475 Å(18)
4.111 Å(16)
3.934 Å(12)
3.395 Å(20)
2.933 Å(18)
2.154 Å(25)

Type Occurrence of ŠtěpiteHide

General Appearance of Type Material:
crystalline crusts of tabular crystals (the crystals are up to 0.6 mm, showing {001} and {100}), that exist in aggregates up to 6 mm; also blocky intergrowths of crystals; minute radiating aggregates of thin plates
Place of Conservation of Type Material:
Department of Mineralogy and Petrology of the National Museum in Prague, Prague, Czech Republic, catalogue number P1P 7/2011
Geological Setting of Type Material:
at the surface of native arsenic lens, at the joint of Geschieber and Geier veins within Ag-As-Bi-Co-Ni-U hydrothermal vein-type deposit
Associated Minerals at Type Locality:

Synonyms of ŠtěpiteHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
3 photos of Štěpite associated with ArsenicAs
2 photos of Štěpite associated with VysokýiteU4+[AsO2(OH)2]4•4H2O
1 photo of Štěpite associated with ArsenoliteAs2O3

Fluorescence of ŠtěpiteHide

Other InformationHide

IR Spectrum:
[cm-1]: 3457 + 3392 (OH-stretching of water and
OH); 1652 (v2 (δ) bending of water); 1402 + 1236
(δ(As-OH) bending); 1076, 1035, + 1004 (probably overtones);
936, 869, 853, 830 + 815 [overlapping bands of v(AsO3OH) stretching]; 75
Raman bands [cm-1]: 3552 + 3484
(OH-stretching of water and OH); 1641 [v2 (δ) bending
vibration of water]; 1490 + 1239 [δ(As‑OH) bending]; 896 + 844 + 811 [overlapping v(AsO3OH) stretching];
760 [v(As-OH) stretching]; 420, 401, 377, 368, 351,
322, 312 [δ(AsO3OH) bending]; 287, 262,
235 [v(OH-O) stretching]; 180, 160, 139, 115, 107 (lattice modes)
Health Risks:

References for ŠtěpiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Plášil*, J., Fejfarová, K., Hloušek, J., Škoda, R., Novák, M., Sejkora, J., Čejka, J., Veselovský, F., Ondruš, P., Majzlan, J., Mrázek, Z. (2012) Štěpite, IMA 2012-006. page 813; Mineralogical Magazine, 76, 807-817.
Plášil, J.; Fejfarová, K.; Hloušek, J.; Škoda, R.; Novák, M.; Sejkora, J.; Čejka, J.; Dušek, M.; Veselovský, F.; Ondruš, P.; Majzlan, J.Z.; Mrázek, Z. (2013): Štěpite, U(AsO3OH)2.4H2O, from Jáchymov, Czech Republic: the first natural arsenate of tetravalent uranium. Mineral. Mag. 77, 137-152.

Internet Links for ŠtěpiteHide

Localities for ŠtěpiteHide

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.
Czech Republic
  • Karlovy Vary Region
    • Karlovy Vary District
[AmMin 84:688]; Ondruš, P., Veselovský, F., Skála, R., Císařová, I., Hloušek, J., Frýda, J., Vavřín, I., Čejka, J., Gabašová, A. (1997): New naturally occurring phases of secondary origin from Jáchymov (Joachimsthal). J. Czech Geol. Soc.: 42(4): 77–108; in: Jambor, J.L., Puziewicz, J., Roberts, A.C. (1999): New mineral names. American Mineralogist: 84: 687
        • Svornost Mine (Einigkeit Mine)
Plášil*, J., Fejfarová, K., Hloušek, J., Škoda, R., Novák, M., Sejkora, J., Čejka, J., Veselovský, F., Ondruš, P., Majzlan, J., Mrázek, Z. (2012) Štěpite, IMA 2012-006. page 813; Mineralogical Magazine, 76, 807-817; Plásil, J.; Fejfarová, K.; Hloušek, J.; Skoda, R.; Novák, M.K; Sejkora, J.; Ejka, J.C.; Dusek, M.; Veselovský, F.; Ondrus, P.; Majzlan, J.Z.; Mrazek, Z. (2013): Štěpite, U(AsO3OH)2.4H2O, from Jáchymov, Czech Republic: the first natural arsenate of tetravalent uranium. Mineralogical Magazine 77, 137-152.
Mineral and/or Locality  
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