Michael Smith

Perthite describes an intimate intergrowth of alkali feldspars, in which sodium plagioclase lamellae, blebs, or droplets exsolve in potassium feldspar.

Syenite is a coarse-grained plutonic rock with intermediate to felsic composition. Its composition and appearance resemble granite but is lower

Myrmekite describes the intergrowth of worm-like or vermicular quartz inside sodium-plagioclase (Na-plagioclase) in plutonic rocks. It usually occurs at the

Rapakivi texture forms when sodium plagioclase overgrows on or rims large, oval to ellipsoidal potassium feldspar phenocrysts. Phenocrsyts are large

Harzburgite is a peridotite primarily made up of olivine, orthopyroxene, and a small amount of clinopyroxenes. Peridotites are coarse-grained, ultrabasic,

Aplite rocks are light-colored intrusive igneous rocks with fine-grained, even, or equigranular sugary or saccharoidal phaneritic texture. Phaneritic implies you

Norite is a coarse-grained, dark-colored plutonic rock of mafic composition. Mafic refers to minerals or rocks rich in iron and

Miarolitic cavities or pods refer to small, irregular cavities in intrusive or plutonic igneous rock, usually lined with well-formed or

The poikilitic texture is an igneous rock texture in which large mineral crystals engulf or completely enclose many smaller ones

While learning about igneous rocks, you often come across the terms ophitic and subophitic textures or fabrics. What do they