Geology Reference
In-Depth Information
B.2.2 Antimony
Antimony is a semimetallic chemical element increasingly being used in the semi-
conductor industry.
Stibnite Sb 2 S 3 its most important ore and occurs in large quantities in
China, South Africa, Mexico, Bolivia and Chile. Other sulphide ores include
ullmanite NiSbS, livingstonite HgSb 4 S 8 , boulangerite Pb 5 Sb 4 S 11 or jamesonite
FePb 4 Sb 6 S 14 . Small amounts of oxide minerals formed by weathering are also
known. Considerable amounts of Sb are obtained as a byproduct derived from lead
and copper refining and especially from the mining of galena. As an alloy, anti-
mony increases lead's durability and mechanical strength. Its compounds are used
to make flame-proofing materials, paints, glass and pottery.
B.2.3 Arsenic
Arsenic is a semi-metallic poisonous element. Its minerals are widely distributed
throughout the world. Small amounts of the free element have also been found.
Most is found in conjunction with ores containing sulphur such as realgar As 4 S 4 ,
orpiment As 2 S 3 , and the oxidised form of arsenolite As 2 O 3 . No quantities are
however mined as such given that it is produced as a byproduct of other metal
production including that of iron, copper, cobalt or nickel. The main economic
source of As is arsenopyrite FeAsS. It can be also recovered from loellingite FeAs 2 ,
sa orite CoAs, nickeline NiAs, cobaltite CoAsS, gersdo te NiAsS or enargite
Cu 3 AsS 4 .
Arsenic compounds are used as insecticides to protect fruit trees, as wood preser-
vatives, in the making of special types of glass and lately, in the semiconductor
gallium arsenade, which has the ability to convert electric current to laser light.
Many other historically used compounds have fallen out of favour due to their toxic
and highly reactive nature.
B.2.4 Barium
Barium is an alkaline-earth metal that is chemically similar to calcium. It is rather
abundant. Its chief mined ore is barite. A subsidiary mineral is barium carbonate
witherite, BaCO 3 .
Barium and its compounds have many industrial uses. Barite, BaSO 4 , for
instance, is extremely important for the petroleum industry, which accounts for
more than 85% of its consumption and where it is used as a weighting agent in
petroleum well-drilling. Barium-nickel alloys are used for spark-plug electrodes
and in vacuum tubes as drying and oxygen-removing agents. Barium nitrate and
chlorate give fireworks their green colour. Other compounds are used to make
bricks, tiles, glass or rubber.
 
Search WWH ::




Custom Search