Ursilite
A synonym
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About Ursilite
Formula:
(Mg/Ca)4(UO2)4(Si2O5)5.5(OH)5 · 13H2O
Lustre:
Vitreous, Silky
Hardness:
2 - 3
Specific Gravity:
3.25 (Calculated)
Crystal System:
Orthorhombic
Name:
The name reflects the URANium and SILicon content.
First Recorded Locality:
Synonym of:
"Ursilite" is now said to be an obsolete name. The correct minerals names are calcioursilite and magnioursilite.
Historically, calcioursilite and magnioursilite were described together in 1957 as “ursilite” from the Oktyabr’skoye deposit, Kyzyltyube-Saj, Samgar Steppe, Tajikistan. The original publication considered two varieties: calcium ursilite ("almost pure Ca-U-silicate") and magnesium ursilite ("almost pure Mg-U-silicate").
The analyses showed Ca >Mg and Mg > Ca. Subsequently, calcioursilite and magnioursilite were defined instead of ursilite, and “ursilite” was officially discredited in 2018.
Historically, calcioursilite and magnioursilite were described together in 1957 as “ursilite” from the Oktyabr’skoye deposit, Kyzyltyube-Saj, Samgar Steppe, Tajikistan. The original publication considered two varieties: calcium ursilite ("almost pure Ca-U-silicate") and magnesium ursilite ("almost pure Mg-U-silicate").
The analyses showed Ca >Mg and Mg > Ca. Subsequently, calcioursilite and magnioursilite were defined instead of ursilite, and “ursilite” was officially discredited in 2018.
Unique Identifiers
Mindat ID:
4119
Long-form identifier:
mindat:1:1:4119:1
GUID
(UUID V4):
(UUID V4):
71438db9-05a6-47b5-a42e-28e16d2816db
IMA Classification of Ursilite
Discredited
IMA Formula:
Mg4(UO2)2(Si2O5)5.5(OH)5 · 13H2O
Approval history:
Pre-2018: Status grandfathered.
Discredited by IMA in April 2018, executive decision taken by the officers of the IMA CNMNC.
Discredited by IMA in April 2018, executive decision taken by the officers of the IMA CNMNC.
Classification of Ursilite
9..
9 : SILICATES (Germanates)
:
:
9 : SILICATES (Germanates)
:
:
Physical Properties of Ursilite
Optical Data of Ursilite
Type:
Biaxial (-)
RI values:
nα = 1.570 nγ = 1.584
Max Birefringence:
δ = 0.014
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Moderate
Chemistry of Ursilite
Mindat Formula:
(Mg/Ca)4(UO2)4(Si2O5)5.5(OH)5 · 13H2O
Crystallography of Ursilite
Crystal System:
Orthorhombic
Cell Parameters:
a = 11.60 Å, b = 14.68 Å, c = 12.83 Å
Ratio:
a:b:c = 0.79 : 1 : 0.874
Unit Cell V:
2,184.80 ų (Calculated from Unit Cell)
Z:
6
Morphology:
Needlelike crystals (only visible in SEM)
Geological Environment
Geological Setting:
Uranium deposit
First Recorded Occurrence of Ursilite
Synonyms of Ursilite
Other Language Names for Ursilite
German:Mg-Ursilit
Ursilit
Ursilit
Spanish:Ursilita
Common Associates
Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
9.. | Chrysotile | Mg3(Si2O5)(OH)4 |
9.. | Hiortdahlite I | Na4Ca8Zr2(Nb,Mn,Ti,Fe,Mg,Al)2(Si2O7)4O3F5 |
9.. | Halloysite-7A | |
9.. | Afanasyevaite | |
9.. | Sodicpedrizite | |
9.. | Sodic-ferropedrizite |
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 Ursilite
mindat.org URL:
https://www.mindat.org/min-4119.html
Please feel free to link to this page.
Please feel free to link to this page.
References for Ursilite
Reference List:
Dara-i-Pioz Massif, Districts of Republican Subordination, Tajikistan