Page 193 - Introduction to Mineral Exploration

176 C.J. MOON

100,000 3000
Cu aqua regia (ppb) 60,000 Cu hydroxylamine (ppb) 2000
80,000

40,000
1000
20,000
0 100 0
500
Cu ammonium acetate (ppb) 400 Cu enzyme leach (ppb) 80

60
300
200
40
20
100

80 0 8000 0 0
Cu deionized water (ppb) 40 Na deionized water (ppb) 6000
60

4000
20
2000
0

Gravel 516,000 517,000 518,000 519,000 520,000 521,000 m
Oxide
Granodiorite and
Sulfide metasedimentary
Porphyry rocks
FIG. 8.17 Comparison of different partial extractions on soil samples across the Gaby Sur porphyry copper
deposit, Chile. (From Cameron et al. 2004.)

plants, in particular flowers associated with This condition is particularly amenable to
mineralisation. The most famous of these is remote sensing from satellites. Most gardeners
the small mauve copper flower of the Zambian appreciate that plants have favorite soil condi-
Copper Belt, Becium homblei. In general this tions and it is possible to make an estimate
plant requires a soil copper content of 50– of bedrock based on the distribution of plant
1600 ppm Cu to thrive, conditions that are species. Unfortunately this method tends to be
poisonous to most plants (Reedman 1979). This rather expensive and is little used.
type of plant is known as an indicator plant.
Unfortunately recent research has demon-
strated that most indicator plants will flourish Biogeochemistry
under other conditions and are not very Plants require most trace elements for their
reliable. survival and take these through their roots,
A more reliable indicator of metal in soils is transpiring any residues from their leaves and
the stunting of plants or yellowing (chlorosis). concentrating most trace elements in their