Kimberlite
Topic: Minerals, Rocks and the Rock Cycle · NCERT: Beyond NCERT
Meaning
Kimberlite is an ultramafic igneous rock, meaning it is very rich in iron and magnesium and low in silica. It forms from magma that starts deep in the mantle and shoots up very quickly through narrow, carrot-shaped channels called pipes. Diamonds form only under the huge pressure found at great depth. Because kimberlite magma rises so fast, it can carry diamonds to the surface before they change into graphite. That is why kimberlite pipes are the main primary source of diamonds.
Example
The Majhgawan pipe near Panna, Madhya Pradesh, is a kimberlite pipe mined for diamonds by NMDC. It lies in the Panna diamond belt of the Vindhyan rocks. Vajrakarur in Andhra Pradesh also has kimberlite pipes.
Don't confuse with
- Placer diamonds: kimberlite is the rock where diamonds first come up. Placer deposits are diamonds (or gold and tin) that weathering has freed and rivers have later left in sand and gravel.