形成于距今约4.3亿年前的志留纪，是目前当地发现的最古老的花岗岩。这种花岗岩的典型特点是岩石由长石、石英、角闪石、黑云母等粗矿物颗粒构成，并发育有长度在 3-5 厘米的钾长石巨晶。

Formed in the Silurian about 430 million years ago, it is the oldest granite discovered in the area. The typical feature of this granite is that the rock is composed of feldspar, quartz, hornblende, biotite and other coarse mineral particles, and megacrysts of K-feldspar develops with a length of 3-5cm.