Adjective
Completely crystalline; -- said of a rock like granite, all the constituents of which are crystalline.
Source: Webster's dictionaryThe word "granite" comes from the Latin granum, a grain, in reference to the coarse-grained structure of such a holocrystalline rock. Source: Internet
It forms when molten magma is trapped beneath the Earth 's surface and slowly cools into a holocrystalline mass. Source: Internet