The types of rocks found in the Himalayas vary widely depending on their specific location, but can be classified into three categories: metamorphic, igneous and sedimentary.
Volcanic, or extrusive, igneous rocks form from lava that has been released above the Earth’s surface, while plutonic, or intrusive, igneous rocks form from magma underneath the ground. Two of the Himalayas’ major rock zones are comprised primarily of igneous plutonic rocks. Specific plutonic rock types in these zones include granite, diorite, gabbro, tonalite, monazite and pegmatite. Alunite is among the few extrusive igneous rocks found in the Himalayas.
Metamorphic rocks present in the Himalayas include schist, migmatite, phyllite, gneiss and amphibolite. Additionally, metamorphosed forms of some sedimentary rocks occur in the region, such as quartzite, a metamorphosed type of sandstone; slate, a metamorphosed form of shale; and marble, a metamorphosed limestone. Some metamorphic rocks in the Himalayas have even been found to contain garnets.