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Roumaite

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Formula:
(Ca,Na,REE,◻)7(Nb,Ti)[Si2O7]2OF3
Colour:
colorless
Lustre:
Silky
Specific Gravity:
3.33 (Calculated)
Crystal System:
Monoclinic
Name:
For the type locality.
This page provides mineralogical data about Roumaite.


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Classification of RoumaiteHide

Approved
Approval Year:
2008

Physical Properties of RoumaiteHide

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

Chemical Properties of RoumaiteHide

Formula:
(Ca,Na,REE,◻)7(Nb,Ti)[Si2O7]2OF3
IMA Formula:
(Nb,Ti)(Ca,Na,◻)3(Ca,REE)4(Si2O7)2(OH)F3

Crystallography of RoumaiteHide

Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Space Group:
Bb
Setting:
Cc
Cell Parameters:
a = 7.473 Å, b = 11.294 Å, c = 18.778 Å
β = 101.60°
Ratio:
a:b:c = 0.662 : 1 : 1.663
Unit Cell V:
1,552.49 ų (Calculated from Unit Cell)
Z:
4

X-Ray Powder DiffractionHide

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)

Type Occurrence of RoumaiteHide

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.
Associated Minerals at Type Locality:

Synonyms of RoumaiteHide

Relationship of Roumaite to other SpeciesHide

Other Members of this group:
Batievaite-(Y)Y2Ca2Ti(Si2O7)2(OH)2(H2O)4Tric. 1 : P1
Fogoite-(Y)Na3Ca2Y2Ti(Si2O7)2OF3Tric. 1 : P1
GötzeniteNaCa6Ti(Si2O7)2OF3Tric. 1 : P1
GrenmariteNa4MnZr3(Si2O7)2O2F2Mon. 2/m : P2/b
Hainite-(Y)Na2Ca4(Y,REE)Ti(Si2O7)2OF3Tric. 1 : P1
KochiteNa3Ca2MnZrTi(Si2O7)2OF3Tric. 1 : P1
Mosandrite-(Ce)(Ca3REE)[(H2O)2Ca0.50.5]Ti(Si2O7)2(OH)2(H2O)2Mon. 2/m : P21/b
Nacareniobsite-(Ce)NbNa3Ca3(Ce,REE )(Si2O7)2OF3Mon.
Rinkite-(Ce)(Ca3Ce)Na(NaCa)Ti(Si2O7)2(OF)F2Mon.
Rinkite-(Y)Na2Ca4YTi(Si2O7)2OF3Mon. 2/m : P21/b
RosenbuschiteNa6Ca6Zr3Ti(Si2O7)4O2F6Tric. 1 : P1
SeidozeriteNa4MnZr2Ti(Si2O7)2O2F2Mon.
Structurally related to group(s):

Fluorescence of RoumaiteHide

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 RoumaiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
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 RoumaiteHide

Localities for RoumaiteHide

ⓘ - 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.
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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