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Tantalum is
found mainly in the minerals tantalite [(Fe,Mn)Ta2O6] (easily confused
with columbite, the niobium analogue of tantalite) and euxenite. Ores
are found in Australia, Brazil, Mozambique, Thailand, Portugal, Nigeria,
Congo,Canada and Tanzania. It is also a byproduct from the extraction of
tin.
Tantalite is the most spread tantalum mineral and makes
for an important ore for the industrially useful metal. Tantalum is used
in alloys for strength and higher melting points, in glass to increase
the index of refraction, and in surgical steel, as it is non-reactive
and non-irritating to body tissues.
Tantalite forms a series with
the mineral columbite. In fact the two are often grouped together as a
semi-singular mineral called columbite-tantalite in many mineral guides.
A series is where two or more elements can occupy the same places within
a crystal structure and their respective percentages can then
vary.
The two minerals of this series have similar
properties since they have the same structure and similar chemistries
(tantalum and niobium are very similar elements). Tantalite is the more
tantalum rich end member and columbite is the more niobium rich end
member. Niobium had been called columbium hence the name
columbite.
Tantalite?s greatest difference from columbite is its
much greater specific gravity, 8.0+ compared to columbite?s 5.2. Other
properties that vary slightly are color, transparency and streak. Both
minerals can be found more or less together in granite pegmatite?s rich
in lithium and phosphorus minerals with columbite concentrated at the
edges of the pegmatite and tantalite enriched in the
core.
| Colour |
Dark black, iron-black to dark brown or even reddish
brown |
| Luster |
Submetallic to almost resinous |
|
Transparency |
Crystals are nearly opaque being transparent in thin
splinters. |
| Crystal System |
Orthorhombic; 2/m 2/m 2/m |
|
Crystal Habits |
stubby prismatic crystals with
complexly |
| Cleavage |
Good in one direction |
| Fracture |
Subconchoidal |
|
Hardness |
6
- 6.5 |
| Specific Gravity |
Approximately 8.0+ when pure (very heavy for
non-metallic minerals) |
|
Streak |
Brownish-red to black |
| Other Characteristics |
Some specimens may show a bluish iridescent tarnish
and demonstrate weak magnetism |
|
Associated Minerals |
albite, spodumene, cassiterite, microcline,
lepidolite, apatite, beryl, microkite, tourmalines and
amblygonite
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Please
Ask For
Tantalite
Stocks
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SOURCES FOR THIS GEMSTONE
Brazil, Zambia,Tanzania, U.S.,
Canada, India, Sri Lanka and Madagascar, Congo ,Tanzania |
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