What is the term used when constituents are crystallized completely?

What can be said about the grain size of pegmatite?

Rock salt may be formed by ________

What is the range of grain size for coarse grained igneous rock?

Structure involving porphyroblasts is ________

The grade of coal with very low calorific value is ________

Which of these rocks is the latest rock?</p>

What is the hardness of the lignite grade of coal?