Hostname: page-component-76fb5796d-22dnz Total loading time: 0 Render date: 2024-04-25T17:07:46.161Z Has data issue: false hasContentIssue false
  • English
  • Français

Rutile and apatite: Useful prospecting guides for porphyry copper deposits

Published online by Cambridge University Press:  05 July 2018

Sidney A. Williams  and
Fabien P. Cesbron
Sidney A. Williams
Affiliation:
Phelps Dodge Corporation Douglas, Arizona, U.S.A.
Fabien P. Cesbron
Affiliation:
Phelps Dodge Corporation Douglas, Arizona, U.S.A.
Get access Rights & Permissions [Opens in a new window]

Summary

The accessory minerals rutile and apatite have been studied in 77 known porphyry copper deposits. Their value as indicators has been well established on the basis of specific chemical and paragenetic variations which they show.

Rutile occurs as the only Ti-mineral in the quartz-sericite zone, is dominant in the biotite-orthoclase zone, and is generally found in the inner fringes of the chlorite-epidote zone. It forms in these zones mainly as a result of the destruction of sphene, but also from biotite and hornblende.

The length: width ratio of rutile crystals is 1·5:1 in the centre of a porphyry system, increasing gradually outward to 2:1. A characteristic red colour displayed in thin section is attributed to a high copper content ranging from 100 to 500 ppm. The ratio of Cr+V:Nb+Ta is also unusually high.

Apatite shows evidence of a complicated history of corrosion and redeposition accompanied by outward migration during the life of the porphyry system. The migration parallels that of copper and typically extends far into the host rocks. The apatite is enriched in chlorine. A plot of a versus c shows a clear separation of apatites of various genetic types, including tin and molybdenum porphyries.

Type
Short Communications
Information
Mineralogical Magazine , Volume 41 , Issue 318 , June 1977 , pp. 288 - 292
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1977

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Banks, (N. G.), 1976. Halogen contents of igneous minerals as indicators of magmatic evolution of rocks associated with the Ray Porphyry Copper deposit, Arizona. J. Res. U.S. Geol. Surv. 4, 91–117.Google Scholar
Carson, (D. J. T.) and Jambor, (J. L.), 1974. Mineralogy, zonal relationships and economic significance of hydro-thermal alteration at porphyry copper deposits, Babine Lake Area, British Columbia. Can. Inst. Min. Metall. Bull., Feb. 1-24.Google Scholar
Sotnikov, (V. I.), Nikitina, (Y. I.), Lavrent'ev, (Y. G.), and Semenov, (V. I.), 1971. Some characteristics of accessory apatite from the explosion-breccia zone of the Zhirekenskoye deposit, eastern Transbaikal. Dokl. akad. nauk. SSSR, 200, 193-6.Google Scholar
Taborsky, (F. K.), 1972. Chemismus und Optik dcr Apatite. Neues Jahrb. Mineral., Monatsh. 79-91.Google Scholar