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| Betafite
is named for the the locality near Betafo District, Antananarivo Province, Madagascar
where it was discovered.
| Discovered
in 1912;
IMA
status: Valid (IMA approved 1961) |
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Chemistry
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Chemical
Formula: |
(Ca,U)2(Ti,Nb,Ta)2O6(OH)
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Calcium Uranium
Titanium Niobium Tantalum Oxide Hydroxide |
Molecular
Weight: |
415.12 gm
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Composition: |
Calcium |
1.93 % |
Ca |
2.70 % |
CaO |
|
Uranium |
17.20 % |
U |
20.67 % |
UO3 |
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Tantalum |
21.79 % |
Ta |
26.61 % |
Ta2O5 |
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Titanium |
9.23 % |
Ti |
15.39 % |
TiO2 |
|
Niobium |
20.14 % |
Nb |
28.81 % |
Nb2O5 |
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Aluminum |
0.65 % |
Al |
1.23 % |
Al2O3 |
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Iron |
1.35 % |
Fe |
1.92 % |
Fe2O3 |
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Hydrogen |
0.73 % |
H |
6.51 % |
H2O |
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Oxygen |
26.98 % |
O |
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|
100.00 % |
|
100.00 % |
= TOTAL OXIDE |
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Classification
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Mineral
Classification: |
Oxides
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Strunz 8th
Ed. ID:
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4/C.16-10
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Nickel-Strunz 10th
Ed. ID:
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4.DH.15
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4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar H : With large (+- medium-sized) cations; sheets of edge-sharing octahedra
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Related
to: |
Pyrochlore
Supergroup. Pyrochlore Group. Betafite Subgroup. The calcium analogue of the other members of the Betafite Subgroup.
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Members
of Supergroup: |
Pyrochlore
Supergroup: Betafite Group, Elsmoreite Group, Microlite
Group, Pyrochlore Group, Romérite Group
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Members
of Group: |
Pyrochlore
Group: Fluorcalciopyrochlore, Fluorkenopyrochlore, Fluornatropyrochlore,
Fluorstrontiopyrochlore, Hydropyrochlore, Hydroxycalciopyrochlore,
Kenoplumbopyrochlore, Oxycalciopyrochlore, Oxynatropyrochlore,
Oxyplumbopyrochlore, Oxyyttropyrochlore-(Y)
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Members
of Subgroup: |
Betafite Subgroup:
Oxycalciobetafite, Oxyuranobetafite
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Varieties: |
Aluminian
Betafite, Barian Betafite, Tangenite
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Synonyms: |
Blomstrandite,
Mendeleyevite, Mendelyeevite, Samiresite, Tantalbetafite,
Titanbetafite
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Crystal
Data
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Crystallography:
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Isometric
- Hexoctahedral
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Crystal
Habit:
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Crystals
commonly octahedra modified by [110], [100], [113],
[233], and [230]; some crystals elongated k [001] or
[111]; to 15 cm.
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Twinning:
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None
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Physical
Properties
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Cleavage: |
None
observed
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Fracture: |
Conchoidal
to Irregular/Uneven
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Tenacity:
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Brittle
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Moh's
Hardness: |
3.0
- 5.5
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Density:
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3.70
- 4.90 (g/cm3)
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Luminescence:
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Radioactive
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Radioactivity:
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Very
Strong;
GRapi = 1,310,418.25 (Gamma Ray American Petroleum Institute Units)
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Health
Warning: |
Contains Uranium - always wash hands after handling. Avoid inhaling dust when
handling or breaking. Never lick or ingest. Avoid prolonged exposure in
proximity of the body. Store away from inhabited areas. |
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Optical
Properties
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Color: |
Red;
Greenish Brown, dark Brown to Black when metamict, commonly
superficially altered Yellow; almost Colorless in transmitted
light.
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Transparency: |
Translucent
to Opaque
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Luster: |
Waxy,
Greasy
to Adamantine, Semimetallic
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Refractive
Index: |
1.910
- 2.197 Isotropic
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Birefringence: |
0.000
(Isotropic)
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Dispersion: |
None
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Pleochroism: |
None
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Reflectivity: |
(400)
13.5, (420) 13.2, (440) 13.0, (460) 12.8, (480) 12.6,
(500) 12.4, (520) 12.3, (540) 12.2, (560) 12.0, (580)
11.9, (600) 11.7, (620) 11.6, (640) 11.6, (660) 11.6,
(680) 11.5, (700) 11.5
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Occurances
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Geological
Setting: |
Typically
a primary mineral in granite pegmatites; rare in carbonatites.
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Common
Associations: |
Allanite,
Beryl, Biotite, Magnetite, Microcline, Quartz, Thorite,
Titanite, Zircon |
Common
Impurities: |
Al,
Fe, K, Mg, Pb, REE, Sn, Ta, Th, W, Zr |
Type
Locality: |
Ambolotara, Betafo
Commune, Betafo District, Vakinankaratra Region (Betafo - Antsirabé
region), Antananarivo Province, Madagascar |
Year
Discovered: |
1912 (IMA approved
1961) |
View
mineral photos: |
Betafite
Mineral Photos and Locations |
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More
Information
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|
Mindat.org
Webmineral.com
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Betafite is
a very rare gem that is highly radioactive. It is mainly
for collectors of very unusual gems or
radioactive
gems. It is one of the few uranium bearing minerals
to form as well shaped crystals. Betafite is one of
several so called Rare Earth Oxides. Other rare
earth oxides such as Aeschynite-(Y),
Euxenite-(Y),
Fergusonite-(Ce)
and Samarskite-(Y)
have similar properties but do not form as well shaped
crystals like those typical of Betafite. Betafite was discovered in 1912 at Ambolotara,
Betafo District, Madagascar. It is a member of the Pyrochlore Group
that typically occurs as a primary mineral in granite
pegmatites, rarely in carbonates.
Sources
of Betafite: In Madagascar, large crystals at a number
of localities, including: from Ambolotara, west of Betafo;
Ambatolampikely; Ambatofotsy; Ambatomboahangy; Ambalahazo;
Tomboarivo; and Antanifotsy. In Norway, at Höysjċen,
near Kragerĝ; Landsverk quarry, near Evje; and Ljosland.
From Slyudyanka, near Lake Baikal, Siberia, Russia.
In the Silver Crater mine, Wilberforce, Ontario, and
elsewhere in Canada. In the USA, in the Brown Derby
pegmatite, Gunnison County, Colorado; in the Pidlite
pegmatite, Mora County, New Mexico; and from the Cady
Mountains, San Bernardino County, California.
Betafite
is a highly radioactive mineral and should be stored
away from other minerals and gems that might be damaged
by radioactivity. Human contact and exposure to Thorite
mineral specimens or gems should be limited!
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Betafite
gems for sale:
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yet. Please
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