Forelesninger holdt ved Advanced Study Institute of Feldspar - Oslo 1962
Lectures held at Advanced Study Institute of Feldspar - Oslo 1962

A rock is the result of a series of completed processes. Whatever rock present is far removed from the conditions under which it was formed. Any record of temperature will for these completed processes be obtained by inspection of the cold rock. We have to look for some properties indicative of former conditions, indicative of the temperatures that have existed long ago.

The minerals of the rock are the geologic temperature recorders. For granites and gneisses, and generally for quartzo-feldspathic rocks, quartz may be used as a geologic thermometer. For in principle it is possible to find out whether a quartz crystal was formed above or below the α- β inversion point (around 600 °C).