Alkaline K Feldspar In Granite. It is found only in young volcanic discharges or volcanic rocks rhyolite trachyte and dacite. Feldspars crystallize from magma as both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock. Hornblende and biotite are the commonest mafic minerals however muscovite is also frequently encountered.
The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. The feldspar component of syenite is predominantly alkaline in character usually orthoclase.
The differences can be subtle and confusing.
The abundance of k spar gives the rock a predominant pink to reddish hue. The abundance of k spar gives the rock a predominant pink to reddish hue. Syenites are usually either peralkaline with high proportions of alkali elements relative to aluminum or peraluminous with a higher concentration of aluminum relative to alkali elements k na ca. Alkali feldspar granite some varieties of which are called red granite is a felsic igneous rock and a type of granite rich in the mineral potassium feldspar k spar it is a dense rock with a phaneritic texture.
