Obsidian is a naturally occurring volcanic glass created being an extrusive pyrogenic rock and roll.
Group of andesites could be refined based on the the majority of plentiful phenocryst. Example: hornblende-phyric andesite, if hornblende may be the ...
In the world, most basalt magmas get formed aside decompression reduction of the mantle. Basalt normally erupts on Io, your third biggest celestial s...