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Bureau of Mines / Minerals yearbook: Metals and minerals 1978-79
Year 1978-79, Volume 1 (1978-1979)

Baskin, G. David
Gem stones,   pp. 363-375 ff. PDF (1.3 MB)

Page 371

 Angola.—The Angola Diamond Co. mines have been offered. Prices
said to be diamond on concessions comprising 50,000 increasing 20% annually.
It is hoped that square kilometers in the northeastern re- with increased
open cut mining at Lightgion of the country. After a considerable fling Ridge,
this area will eventually rival drop in production because of internal strife
the South Australia production from the in 1976 and 1977, partial recovery
was opal fields at Coober Pedy.h1 
achieved in 1978, with the mining of more Botswana.—The Jwaneng
now than 700,000 carats of gem-quality dia- being developed will reportedly
add 6 mumond.~ A 137-carat diamond was found in lion carats to the annual
diamond producthe Lucapa mine area in North Lunda tion of Botswana by 1985,
making that Province.6 country one of the world's major producers. 
 Australia —Diamond exploration in the ranking behind Zaire and
Soviet Union Kimberley region of Western Australia Located in the Kalahari
Desert, the mine is stirred much excitement during 1978 and a joint project
betweeu the Botswana Gov 1979. More than 5,700 claims of 120 hec- ernment
and De Beers Consolidated Mines tares each were staked by 23 exploration
Ltd. The Government will receive 77.5% of groups representing 45 to 55 different
corn- the profits.12 
panies The most promising results were The diamond mines at Orapa and Letlha
shown by the Ashton Joint Venture, which kane were recently expanded. The
Orapa is managed by a subsidiary of Conzinc mine increased its output from
2.5 million Riotinto of Australia Ltd. Initial sampling to 4.1 million carats,
and an expansion to of several of the 28 kimberlite pipes located the facilities
at Letihakane raised producin 1978 yielded more than 4,200 stones of tion
from 330,000 to 400,000 carats per year industrial and gem-quality. The largest
at the end of 1979. The mines are operated stone found weighed 57 carats
but the by Debswana a joint company owned equal average weight was less than
0.1 carat. In ly by De Beers and the Botswana GovOctober 1979, a group managed
by Conzinc ernment.13 
Riotinto found a pipelike structure of Central African Empire.—Diamond
prodiamond-bearing kimberlite in the Lake duction in 1978 was 284,24~J carats,
70% Argyle area in Western Australia near the being gem-quality. Total production
deNorthern Territory border. The pipe, cover- creased 5.6% from the 1977
level, while ing 111 acres at the surface yields about increased prices resulted
in the value of 150 carats for each 100 metric tons of production rising
49% to $35 million.'~ An kimberlite ore. Alluvial deposits in the Israeli-Iranian-Swiss
group obtained a same area have much higher yield. The 30,000-square-kilometer
concession for diaprospect has yielded more than 5,000 carats; mond exploration
and evaluation; however, the largest stone weighed 7.03 carats. The the group's
project was dissolved when quality of the stones has not been ascertain-
political instability in Iran increased.15 
ed. The claims will not be firmly evaluated Colombia.—In the first
7 months of 1979, until 1980 when more extensive bulk Colombia exported emeralds
worth $75 milsampling and sample processing will be lion. Total production
in 1978 was $40 complete.~ 8 million compared with $2 million in 1973, 
 A large ruby field was discovered at when some state-owned mines at Muzo,
Ambalindum Station northeast of Alice Coscuez, and Penas Blancas, beset by
theft Springs in central Australia. The property and violence, were occupied
by the army. owner has said that it is among the three These have since been
taken over by private most important ruby discoveries in the consortia and
returned to full production.16 world.~ India.—Buying and selling
 A sapphire deposit near Mt. Garnett in came much easier with the formation
of two north Queensland is yielding stones up to 10 new facilities. The Hindustan
Diamond Co., carats. The area has been set aside by the Ltd., has been set
up jointly by the Indian Government for hand miners.'° Government
the Bank of Bermuda's 
 Annual value of opal production at Light- UK branch (30%), and the Industrial
Investning Ridge in northern New South Wales . ment Trust, Ltd. (20%). The
company will has reached $A7 million. Prices up to $5,000 be involved in
obtaining and distributing per carat for black opals are reported to rough
diamonds on a regular basis to the 

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