Pyrometamorphism
Pyrometamorphism is a type of metamorphism in which rocks are changed by heat coming from the fossil fuel fire. The rocks produced by pyrometamorphism include buchite, clinker and paralava, formed due to thermal changes of sedimentary rocks. Both natural and anthropogenic examples of sites with active pyrometamorphism are known. Natural pyrometamorphic rocks are known, e.g., from the Hatrurim Formation. Xenoliths of sedimentary rocks trapped in volcanic lava may undergo pyrometamorphic transformation. Anthropogenic pyrometamorphic rocks are found in burning coal-mining dumps. A great number of minerals, sometimes very rare, are found within these rocks. Of the silicate minerals, the typical ones are especially cordierite, indialite, fayalite, mullite, tridymite and cristobalite, and sekaninaite. Oxide minerals include corundum, hematite, hercynite, magnesioferrite, and magnetite. Some unique minerals typical for meteorites, like oldhamite, are also found in pyrometamorphic rocks.Types of pyrometamorphic rocks
The main types of pyrometamorphic rocks are:
- Buchite – usually referring to fused, partially melted rock, often formed in expense of sandstone; it may have both glassy and vesicular texture
- Clinker – it usually refers to fused, not completely melted, shales; typical feature is preservation of the shaly structure
- Paralava – a product of complete melting and recrystallization
Some thermally changed sedimentary rocks are described under a general name: metapelite.
