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Rankamaite

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JYJ615457

Rankamaite

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Description
Locality: 
Mumba Cassiterite Gravels, Mumba, Masisi Mountains, North Kivu, DR Congo
Class: 
Crystals on Matrix
Size Range: 
Thumbnail (1-3cm)
Size: 
1.2 × 1 × 0.6 cm
Description

Very rare rankamaite, a Ta,Nb bearing oxide,  on altered simpsonite  from the type locality. 

Reference: 

Safiannikoff, A. and van Wambeke, L. (1961): Sur un terme plombifere du groupe pyrochlore-microlite. Bulletin de la Société Francaise de Minéralogie et de Cristallographie 84: 382-384

Mineral Data
What's on the rock

Rankamaite

Formula: 
(Na,K)3(Ta,Nb,Al)11(O,OH)31
Strunz: 
4.DM.05
Crystal System: 
Orthorhombic Water-worn pebbles.
Hardness: 
3.0 - 4.0
Type Locality: 
Mumba cassiterite gravels, Mumba, Masisi Mts, Nord-Kivu, Democratic Republic of Congo (Zaïre)