──────────────────────────────┬───────┬──────┬───────┬───────
│Copper │ Gold │Silver │ Lead
──────────────────────────────┼───────┼──────┼───────┼───────
1. Electrolytic conductivity │ 99·89 │ nil │ nil │ nil
copper, │ │ │ │
2. Lake copper, │ 99·77 │ nil │0·029 │ nil
3. Best select copper, │ 99·75 │ .. │ .. │0·024
4. Tough pitch copper, │ 99·41 │ .. │ .. │0·070
│ 99·25 │ .. │0·36 │0·0103
5. Copper fire-box plate (ran │ │ │ │
500,000 miles, Met. Ry.),│ 98·70 │0·0001│0·0346 │0·4085
│ │ │ │
INTERMEDIATE PRODUCTS— │ │ │ │
Refined converter copper, │ 99·25 │ .. │0·36 │0·0103
│ 99·08 │ .. │0·30 │0·0085
Cathode copper, │ .. │ .. │0·001 │0·00054
Black copper, │ 94·39 │ .. │0·11 │0·19
│ 97·70 │ .. │0·2133 │0·78
Cement copper (Spanish), │ 51·90 │ .. │2·35 │1·45
│ 76·93 │0·10 │ .. │ trace
Blister copper, │ .. │0·0009│0·04 │0·042
Chili bar, │ 98·60 │ .. │ .. │ trace
──────────────────────────────┴───────┴──────┴───────┴───────
──────────────────────────────┬─────────┬────────┬────────┬───────
│ Arsenic │Antimony│ Bismuth│ Iron
──────────────────────────────┼─────────┼────────┼────────┼───────
1. Electrolytic conductivity │ 0·016 │ trace │ nil │0·042
copper, │ │ │ │
2. Lake copper, │ nil │ trace │ nil │0·0077
3. Best select copper, │ 0·025 │ trace │ 0·011 │0·10
4. Tough pitch copper, │ 0·320 │ trace │ 0·010 │0·010
│ 0·0211 │ 0·630 │ 0·0044 │ ..
5. Copper fire-box plate (ran │ │ │ │
500,000 miles, Met. Ry.),│ 0·3726 │ 0·0346 │ 0·0360 │0·0069
│ │ │ │
INTERMEDIATE PRODUCTS— │ │ │ │
Refined converter copper, │ 0·0211 │ 0·0630 │ 0·0044 │ ..
│ 0·0290 │ 0·0254 │ 0·0035 │ trace
Cathode copper, │ 0·00034 │ 0·0008 │ 0·0003 │ ..
Black copper, │ trace │ .. │ .. │ ..
│ 0·052 │ 0·2380 │ 0·0035 │0·17
Cement copper (Spanish), │ 2·95 │ 0·50 │ 0·95 │7·00
│ 1·32 │ 0·02 │ .. │7·6
Blister copper, │ 0·108 │ 0·157 │ 0·055 │0·4
Chili bar, │ 0·100 │ trace │ nil │0·009
──────────────────────────────┴─────────┴────────┴────────┴───────
──────────────────────────────┬────────┬────────┬────────┬───────
│ Nickel │ Tin │ Oxygen │ Sulphur
──────────────────────────────┼────────┼────────┼────────┼───────
1. Electrolytic conductivity │ 0·006 │ .. │ 0·008 │ nil
copper, │ │ │ │
2. Lake copper, │ 0·0146 │ nil │ 0·070 │ ..
3. Best select copper, │ 0·061 │ .. │ 0·143 │ ..
4. Tough pitch copper, │ 0·060 │ .. │ 0·120 │ ..
│ .. │ .. │ 0·284 │ ..
5. Copper fire-box plate (ran │ │ │ │
500,000 miles, Met. Ry.),│ 0·3039 │ .. │ 0·0181 │ 0·0064
│ │ │ │
INTERMEDIATE PRODUCTS— │ │ │ │
Refined converter copper, │ .. │ .. │ 0·284 │ ..
│ .. │ .. │ 0·12 │ 0·01
Cathode copper, │ .. │ .. │ 0·005 │ ..
Black copper, │ 2·04 │ 0·07 │ .. │ 0·80
│ .. │ .. │ .. │ 0·796
Cement copper (Spanish), │ .. │ .. │16·00 │ 5·10
│ .. │ .. │ .. │ 0·48
Blister copper, │ 0·0–0·2│ 0·0–0·5│ .. │ 0·112
Chili bar, │ .. │ .. │ .. │ 0·909
──────────────────────────────┴────────┴────────┴────────┴───────
(2) Sulphide ores supply the bulk of the world’s copper, constituting
upwards of 80 per cent. of the total.
(3) The oxidised ores are found in most copper districts, though
usually to only a limited extent. They are often gossan deposits
produced by weathering or by decomposition of sulphides, hence are
generally found nearer the surface, changing to sulphide with depth.
The supply of copper from oxidised ores, which was at one time very
large, is decreasing rapidly, and the greater proportion of the copper
now obtained from them comes from the more recently developed deposits,
of which those at Tanganyika afford an example.
More than 200 minerals which contain copper are known, but most of them
are unimportant from the smelting point of view. The characteristics of
the more noteworthy may be fully studied from text-books of economic
mineralogy.
=Copper Ores—Native Copper.=—Occurs extensively in the Lake Superior
district of Michigan, in Precambrian rocks, sparingly in New Mexico
and China, but seldom anywhere else in workable quantities by itself.
Copper barilla or copper sand, an impure native metal from Chili, was
formerly of importance. Native copper constitutes about 20 per cent. of
the North American supply. It yields metal of exceptional purity, and
the brands of Lake copper reach a very high standard, both as regards
electrical and mechanical properties. A still purer variety is the
native metal from Yunnan, China.