What is the meaning of "rock forming mineral"?

Question

What is the meaning of "rock forming mineral"?

Answer 1

Brief answer could be:

There are thousands of minerals out of which  hardly 10-12 could be called as common minerals and these " common minerals"  constitute all most all of the common rocks found on the surface and in the interior of the earth.

As a rule their presence or absence is essential to decide the name of the rock and its general expected composition.

Hence these are termed as rock forming minerals.

thnks

Answer 2

Well, I thought that one is a bit self explanatory.

A rock forming mineral is a mineral that is common in all different types of rocks. Minerals that form first under the given composition of magma/lava. Minerals that can have different end members and allows for different proportions of elements in between (ex: Forsterite and Fayalite are the end members of olivines but you can have any ratio of Mg and Fe in between)

The 8 most common ones are:

Quartz

Orthoclase

Plagioclase

Biotite

Muscovite

Olivine

Pyroxene

Amphibole

Answer 3

Any number of minerals makes up a given rock. Granite for instance is made up of, feldspar and quartz. Or lets say the mineral, calcium deposits over time to make limestone . minerals deposit or are combined to make a rock.