正长花岗岩主要矿物成分是肉红色正长石、白色石英、黑色黑云母。花岗岩英文名称granite，源自拉丁文granum，意指颗粒，granite即指组成花岗岩的矿物是颗粒状。岩石矿物粒径不同就有不同的岩石名称。矿物粒径5～10mm的花岗岩叫粗粒花岗岩，0.3～3mm的叫细粒花岗岩。此处细粒正长花岗岩呈脉状侵入早期的粗粒正长花岗岩。

Fine-Grain Syenogranite

The main minerals of syenogranite are flesh pink orthoclase, white quartz and black biotite. The name granite stems from Latin granum meaning grain. Granite means that it is comprised of granular minerals. Rock minerals with different grain sizes result in different rock names. The granite of 5～10mm mineral grain sizes is called as coarse-grain granite, 0.3～3mm one called as fine-grain granite. Here, the fine-grain syenogranite in rock vein invaded into early coarse-grain syenogranite