microcrystalline
/mʌɪkrə(ʊ)ˈkrɪstəlʌɪn
/adjective
(Of a material) formed of microscopic crystals.The extent of change, however, varies considerably, depending on the type of microcrystalline stone and on the heat treatment procedures used....
- Associated minerals include pyrophyllite, lazulite, quartz, various brightly colored iron oxides, barite, and a suite of microcrystalline phosphates.
- This difference is due to the fact that most volcanic rocks are microcrystalline or partly glassy, and thus it is more difficult to classify them by their mineralogical composition.