1) Igneous rock
Found on
https://www.crosswordclues.com/clue/quartz-porphyry
Quartz-porphyry, in layman`s terms, is a type of volcanic (igneous) rock containing large porphyritic crystals of quartz. These rocks are classified as hemi-crystalline acid rocks. ==Structure== The quartz crystals exist in a fine-grained matrix, usually of micro-crystalline or felsitic structure. In specimens, the quartz appears as small rounded....
Found on
http://en.wikipedia.org/wiki/Quartz-porphyry
Quartz porphyry is a widely distributed intrusive igneous rock formed from magma in small (relatively speaking, an area of 5000 square kilometres is 'small' in geological terms) intrusive structures, such as dikes and sills, which were usually formed at no great depth. It is generally light coloured, usually grey, pink, red or violet in colour, and...
Found on
http://www.probertencyclopaedia.com/browse/HQ.HTM
No exact match found.
