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Roumaite

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Formula:
(Ca,Na,REE,◻)7(Nb,Ti)[Si2O7]2OF3
System:
Monoclinic
Colour:
colorless
Name:
For the type locality.

Classification of Roumaite

Approved
Approval Year:
2008
mindat.org URL:
http://www.mindat.org/min-38702.html
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Type Occurrence of Roumaite

General Appearance of Type Material:
very small acicular crystals.
Place of Conservation of Type Material:
Museum National d'Histoire Naturelle, 61, rue Buffon, F-75005 Paris, France, catalogue # MNHN208.1; cotype material is deposited in the mineralogical collection of Museo di Storia Naturale e del Territorio, Universita di Pisa, Via Roma 79, Calci (PI), Ita
Geological Setting of Type Material:
a late-stage product of hydrothermal activity in the cavities of nepheline syenites.

Physical Properties of Roumaite

Silky
Diaphaneity (Transparency):
Transparent
Colour:
colorless
Streak:
white
Tenacity:
Brittle
Density:
3.33 g/cm3 (Calculated)

Crystallography of Roumaite

Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Space Group:
Bb
Space Group Setting:
Cc
Cell Parameters:
a = 7.473Å, b = 11.294Å, c = 18.778Å
β = 101.60°
Ratio:
a:b:c = 0.662 : 1 : 1.663
Unit Cell Volume:
V 1,552.49 ų (Calculated from Unit Cell)
Z:
4
X-Ray Powder Diffraction Data:
d-spacingIntensity
3.057 (100)
2.790 (40)
2.689 (46)
2.567 (44)
2.021 (68)
2.004 (33)
1.813 (33)
1.680 (60)

Chemical Properties of Roumaite

Formula:
(Ca,Na,REE,◻)7(Nb,Ti)[Si2O7]2OF3
All elements listed in formula:

Relationship of Roumaite to other Species

Structurally related to group(s):

Other Names for Roumaite

Name in Other Languages:

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.

References for Roumaite

Reference List:
Biagioni, C., Bonaccorsi, E., Merlino, S., Parodi, G.C., Perchiazzi, N., Chevrier, V., Bersani, D. (2010) Roumaite, (Ca,Na,)3(Ca,REE,Na)4(Nb,Ti)[Si2O7]2(OH)F3, from Rouma Island, Los Archipelago, Guinea: a new mineral species related to dovyrenite. The Canadian Mineralogist, 48, 17-28.

Internet Links for Roumaite

Localities for Roumaite

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.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
Guinea (TL)
 
  • Los Archipelago (Los Islands)
Biagioni, C., Bonaccorsi, E., Merlino, S., Parodi, G.C., Perchiazzi, N., Chevrier, V. & Bersani, D. (2010). Roumaite, (Ca,Na,)3(Ca,REE,Na)4(Nb,Ti)[Si2O7]2(OH)F3, from Rouma Island, Los Archipelago, Guinea: a new mineral species related to dovyrenite. Canadian Mineralogist, 48, 17-28.
Mineral and/or Locality  
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