There are many types of rocks beneath Kuching City. One of the most common rocks is Phyllite, spreading from Kuching River Front to many other parts of the city. You will not be able to find beautiful rock cores out of the conventional drilling.
The rock is grey with a characteristic silvery sheen.
Although the rock appears to make up of broken pieces, but do not expect driven concrete piles to penetrate. Standard penetration tests often produce N= more than 50 blows per 10mm. Concrete piles find difficulty to penetrate even with N=30 blows per 300mm.
