• Chemical Formula: (Ca, Na, U)2(Ti, Nb, Ta)2O6(OH, F) , Calcium Sodium Uranium Titanium Niobium Tantalum Oxide Hydroxide Fluoride.
  • Class: Oxides and Hydroxides
  • Group: Pyrochlore
  • Uses: A minor ore of rare earth elements and uranium and as mineral specimens.
  • Specimens

Betafite is a popular uranium bearing mineral to collect. It is one of the few uranium minerals to form nice well shaped crystals. Betafite crystallizes in the isometric symmetry class and forms large octahedral and dodecahedral crystals that can weigh up to 100 kg. Frequently they are modified by other isometric forms and/or flattened when two opposing faces dominate the crystal. Well formed crystals of betafite are considered classics!

Because betafite has rare earth elements such as thorium in its chemistry, it is one of several so called Rare Earth Oxides. Other rare earth oxides such as fergusonite, euxenite, aeschynite and samarskite have very similar properties to each other but lack betafite's typically well formed isometric crystals.

Betafite is formed in rare earth rich, granite pegmatites, a slow cooling igneous intrusive rock, such as from the site in which it was named; Betafo, Malagasy Republic, Madagascar. It is also found in the contact metamorphic marbles that surround these pegmatites. Although concerning the marbles there is a question as to whether they are actually the product of igneous carbonatites. As is the case at the other most notable locality for betafite; Bancroft, Ontario, Canada. At these and other localities, betafite is associated with several minerals common to these rocks such as quartz, feldspars, columbite, tantalite, zircon, biotite, thorite, allanite, fergusonite and other rare earth minerals.

Betafite is a popular and interesting mineral. Although lacking in color, it makes up for it in the large well formed crystals for which it is known. Remember, this is a radioactive mineral and should be stored away from other minerals that are subject to damage from radioactivity and of course human exposure should be limited !


  • Color is black with a tint of yellow, brown or green.
  • Luster is earthy to metallic and sometimes vitreous when translucent.
  • Transparency: Crystals are generally opaque but some translucent specimens are known.
  • Crystal System is isometric; 4/m bar 3 2/m
  • Crystal Habits typically include octahedral and dodecahedral crystals that are often modified by other isometric forms and/or flattened when two opposing faces dominate the crystal; also found as granular and massive. Some crystals can be quite large and can weigh up to and slightly over 100 kg.
  • Cleavage is absent.
  • Fracture is conchoidal.
  • Hardness is 4 - 5.5
  • Specific Gravity is approximately 3.7 - 5.0 (heavy for non-metallic, average for metallic minerals). Extreme variation caused by variable composition of component metals.
  • Streak is yellow to brown.
  • Other Characteristics: Slightly radioactive and crystals/specimens are often coated with a yellow or green earthy coating.
  • Associated Minerals include quartz, feldspars, columbite, tantalite, zircon, biotite, thorite, allanite, fergusonite and other rare earth minerals.
  • Notable Occurrences include Betafo (hence the name), Malagasy Republic, Madagascar; Silver Crater Mine, Bancroft, Ontario, Canada and less noteworthy sites in Russia; Spain; Peru; Pakistan; India; China; Norway and Brazil as well as California, Arizona, New Mexico and Colorado, USA.
  • Best Field Indicators are crystal habit, luster, fracture, color, radioactivity, associations, environment and specific gravity.
BETAFITE specimens:
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BETAFITE specimen btf-1
$ 80.00
Dims: 1.2 x 1.2 x 1.0" (3.0 x 3.0 x 2.5 cm)
Wt: 1.46 oz. (41.5 g) w/ base
Silver Crater Mine, Bancroft, Ontario, Canada
This small specimen consists of 3 partly intergrown Betafite crystals. One of these crystals is not more than 50% complete, and another is about 75% complete, but the largest is essentially whole (though visibly damaged) and has a diameter of about 1" (2.5 cm). Its crystal form is an octahedron modified by a cube. The accompanying bit of matrix is massive calcite with apatite and biotite, and the salmon color is due to the calcite being affected by the radiaion. It is hot-glued onto a flat acrylic base.
no photo
btf-1 ($ 80.00)
Silver Crater Mine, Bancroft, Ontario, Canada
BETAFITE specimen btf-2
$ 225.00
Dims: 2.4 x 1.7 x 1.1" (6.0 x 4.2 x 2.7 cm)
Wt: 2.6 oz. (73 g)
Silver Crater Mine, Bancroft, Ontario, Canada
Three intergrown Betafite crystals rest on the calcite base of this small cabinet piece. The largest of these crystals is much larger than the other two, and has dimensions of 0.9 x 0.9 x 0.9" (2.4 x 2.3 x 2.3 cm). The next in size is less than half that large, and the third does not exceed 0.2" (4 mm) along any axis. All are in excellent condition, showing very little damage, though the cluster as a whole was separated from the base and then re-attached. All have excellent isometric dodecahedral form and the standard black color, though they are all rust-stained. Their luster is dull, and all are certainly opaque. The calcite base is also rust-stained and contains a few more broken, incomplete Betafites.
no photo
btf-2 ($225.00)
Silver Crater Mine, Bancroft, Ontario, Canada
BETAFITE specimen btf-3
$ 225.00
Dims: 1.7 x 1.6 x 1.5" (4.4 x 4.0 x 3.8 cm)
Wt: 3.7 oz. (105 g)
Silver Crater Mine, Bancroft, Ontario, Canada
This excellent hand specimen consists of two Betafite crystals- one partial, one complete- that are partly embedded in two intersecting, incomplete apatite prisms. The complete crystal measures nearly 1" (2.5 cm) in diameter and is in perfect condition, as it does not show even minor damage. Its dodecahedral form is excellent, though a few rhombic faces are slightly modified to a hexagonal shape. Its color is a dull red-brown and its luster is dull. It is, of course, completely opaque. The apatites that form the base show excellent trigonal form but are heavily damaged and missing their terminations. There is no other material present.
no photo
btf-3 ($225.00)
Silver Crater Mine, Bancroft, Ontario, Canada
BETAFITE specimen bet-4
$ 60.00
Dims: 1.3x0.9x0.9" (3.2x2.4x2.3cm)
Wt: 1.35 oz. (38.2g)
Silver Crater Uranium Mine, Bancroft, Ontario, Canada
This dark brown, opaque crystal is betafite, one of the uranium minerals. Note that it is quite radioactive, although it is safer than other uranium minerals that are fibrous or powdery and thus more likely to be inhaled. The crystal is well formed, but is not a pure dodecahedron and is not complete - only 10 faces are visible. Still, it looks rather like a dark brown garnet at first glance. The faces are somewhat weathered, and the bottom of the crystal was broken long before the crystal was mined, judging by its weathered appearance.
no photo
bet-4 ($ 60.00)
Silver Crater Uranium Mine, Bancroft, Ontario, Canada
BETAFITE specimen btf-5
$ 30.00
Dims: 0.64x0.58x0.41" (1.63x1.47x1.04cm)
Wt: 0.14oz (3.94g)
Betafo, Madagascar
Although this thumbnail specimen is incomplete, it is still a very nice octahedral crystal of betafite. The form is slightly modified in that several of the faces are stepped, either due to the way the crystal grew, or possibly because this is several intergrown crystals that are nearly aligned. Betafite is a black mineral, as is this, although it has a yellow earthy coating that is commonly found on weathered betafite crystals. Careful examination reveals several areas where the black betafite shows through the coating.
no photo
btf-5 ($ 30.00)
Betafo, Madagascar


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