Melanocratic

A melanocratic rock contains at least 60% dark and heavy ferro-magnesium minerals. 

 

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What is melanocratic in geology?

 

Source : moviecultists.com

of igneous rock. : having predominantly dark mineral constituents — compare leucocratic, mesocratic.

Which rock has melanocratic colour?

igneous rock

…to as such or as leucocratic. The mafic minerals include olivine, pyroxenes, amphiboles, and biotites, all of which are dark in colour. Mafic minerals are said to be melanocratic. These terms can be applied to the rocks, depending on the relative proportion of each type of mineral present.

 

What does leucocratic mean?

of a mineral or rock. : having a light color — compare melanocratic, mesocratic.

What is Colour index in geology?

The color index of an igneous rock is a measure of the ratio of dark colored, or mafic, minerals to light colored, or felsic, minerals. ... Speaking broadly, mineral colour points out the specific gravity of the mineral, as minerals that are lighter in color tend to weigh less.

Why igneous rocks are dark in Colour?

Colour index, in igneous petrology, the sum of the volume percentages of the coloured, or dark, minerals contained by the rock. ... Darker minerals typically contain more of the relatively heavy elements, notably iron, magnesium, and calcium.