PERIDOTITE

Rock Type: Iron Ore/Ultramafic
Province: Crocker Range
Age: Middle Miocene – Pliocene (13.82 – 2.58 million years ago)
Origin: Kg Polumpung Melangkap, Kota Belud, Sabah

* Peridotite, a coarse-grained ultramafic igneous rock, primarily forms through the crystallization of magma deep within the Earth's mantle and is not common to be found in surface exposure.

* Peridotite can be brought to the Earth’s surface through tectonic processes like mantle upwelling at mid-ocean ridges or in ophiolite complexes.

* Its characteristic green to black color stems from the abundance of olivine and pyroxene minerals. Peridotite exhibits a granular texture due to its coarse crystalline structure, resulting from slow cooling and solidification of the molten rock.

* Serpentinization, a transformative process, occurs when peridotite undergoes hydration, reacting with water to produce serpentine minerals, such as lizardite, chrysotile, and antigorite.

* Serpentinization not only changes the mineral composition but also influences the rock's color, turning it into shades of green. This alteration process often results in a softer, greasy feel to the peridotite.