Platinum
Elemental
Platinum
Pt
Due to its rarity, platinum is more highly priced than gold or
silver.
The History Says
The Spaniards named platinum as 'platina,' or 'little silver,' when
they first encountered it in Colombia. They regarded platinum as an
unwanted impurity in the silver they were mining, and often discarded
it.
The Present Scenario
Platinum is produced commercially as a by-product of nickel ore
processing in the Sudbury deposit.
WELL
FORMED platinum crystals are very rare. The common habit of it is
nuggets and grains. In nature, pure platinum is unknown. Usually it is
alloyed with other metals, like iron, copper, gold, nickel, iridium,
palladium, rhodium, ruthenium and osmium.
These metals presence with platinum tends to lower the density of
platinum. Iron presence leads to a slight magnetism in platinum
nuggets and is common enough property to be considered diagnostic.
Platinum is resistance to chemical attack. It has excellent
high-temperature characteristics, and stable electrical properties.
These properties of platinum is exploited for industrial applications.
It does not oxidise in air at any temperature and is also insoluble in
hydrochloric and nitric acid, but in aqua regia, it does dissolves
forming chloroplatinic acid.
Element platinum is very scarce in most crustal rocks. It is barely
seen as even a trace element in chemical analysis of these rocks. It
seems that platinum is much more concentrated in the mantle and it can
be enriched through magmatic segregation.
The origin of platinum in the earth's crust is from ultra-mafic
igneous rocks and is therefore, can be associated with minerals which
are common to these rocks, like chromite and olivine. However,
platinum's most common source is from placer deposits.
Platinum is more expensive than gold, approximately twice. Its price
changes along with its availability. In the 18th century, the rarity
of platinum made King Louis XV of France declare it to be the only
metal fit for a king.
Physical Characteristics of Platinum
| Color |
White-gray to
silver-gray. |
| Luster |
Metallic |
| Transparency |
Opaque |
| Cleavage |
None |
| Fracture |
Jagged |
| Hardness |
4-4.5 |
| Specific gravity |
14 - 19+, pure platinum is
21.5. |
| Streak |
Steel-gray |
| Tenacity |
Ductile and Malleable |
Uses of Platinum
- In
electronics and scientific apparatus.
- As
jewelry.
- In
dentistry.
- As
catalyst in petroleum refining.
- In
car exhaust anti-pollution devices.
- In
platinum resistance thermometers.
Note:-
Platinum is only used where another element cannot replace its use
because it is very rare.
Associated Minerals of Platinum
- Chromite
- Olivine
- Enstatite
- Pyroxene
- Magnetite
- Gold
(occassionally)
Occurrences of Platinum
- Transvaal,
South Africa.
- Ural
Mountains, Russia.
- Columbia
and Alaska, USA.
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