Dark Grey Mudstone

Dark Grey Mudstone is one of the most common Sedimentary rocks in Sarawak, especially at the Central and Northern Sarawak. It can be massive but quite often in alternate layers with Sandstone, Siltstone and Shale. This Sample was obtained, however, from the Western Sarawak.

Light Grey Conglomerate

You would think that this is a poor concrete core.
No, it was extracted 11m depth below the ground, not far from the junction of Pan Borneo trunk road to Simunjan.

It is not a common sedimentary rock, characterised by cemented gravels and cobbles. The gravels appear to be only slightly rounded, indicating that it did not roll down the stream long enough before it got buried and cemented.

If the fragments are finer, angular and irregular, then the rock is called Breccia.

Light Brown and Grey Sandstones

Sandstone rocks are sedimentary rocks commonly found beneath Sarawak ground, from Kuching to Miri.

This light brown Sandstone core is extracted from about 23m depth.

This light grey Sandstone core fractured to halves, was extracted from about 12m depth.

Brownish Orange Mudstone

The rock sample looks more appealing with bright multi-colours. It is not often encountered with this colour for the fine grained sedimentary rock.

Another Sample of Andesite

Although this grey and light green volcanic rock is highly weathered, it is still very hard and heavy. It was extracted about 10m depth below ground level near Serian county.

Andesite at Serian Hill

It was identified by Geological Department that the rock found at the Serian Hill, Andesite. This rock is another most common igneous rock after Granite and Basalt. To identify the rock type, microscope is required to identify the minerals (petragraphy). When cut open, the surface  is very smooth, and the colour is light bluish and grey, fine grained and crystallised.
The name Andesite originated from the South America's Andes and is associated with lava flows or volcanic activities.