It's got lower aluminium and more magnesium relative to silicon, so it has a lower abundance of feldspar [minerals], and so it has clearly undergone a unique geological history.
Yunnan Province is rich in aluminium mineral resources. Main minerals products can be divided into two types. That is, sedimentary bauxite and nepheline syenite.
云南的铝矿资源丰富，主要矿产分为沉积型铝土矿和霞石正长岩铝资源两大类。
3
The main structure unit of clay minerals contains silicon-oxygen tetrahedron and aluminium-oxygen octahedron.