What are Primary Minerals?

By BYJU'S Exam Prep

Updated on: November 9th, 2023

Primary minerals are those that are created as a result of molten lava crystallizing. Silica and silicate minerals comprise most of the soil’s fundamental minerals. Primary minerals such as quartz, feldspar, plagioclase, muscovite, biotite, amphibole, pyroxene, and olivine are present in intrusive rocks like granite, granodiorite, gabbro, and peridotite.

Primary Minerals

Primary minerals are also present in extrusive rocks like basalt, rhyolite, andesite, and obsidian in varying concentrations. The physical characteristics of Primary minerals are the kind of external features that are visible clearly and can be judged by the outer appearance. These are Crystal, Cleavage, Fracture, Tenacity, and Luster. The detailed information has been presented below:

Kind of External Crystal:

The internal arrangement of the molecules determines the outward crystal form, which might take the shape of cubes, octahedrons, hexagonal prisms, etc. Let us read in detail about these external features separately.


It means a crystal splits in a straight line. Not all minerals show cleavage and a weak point in the structure of a mineral is liable to split. The nature of a mineral’s visible surface and its ease of cleavage are both revealed by the quality of the mineral’s cleavage.


A fracture occurs when a mineral sample is split in a way that does not operate as a plane of perfect or precise cleavage. When a mineral is broken apart or crushed, it fractures.

  • Planar surfaces that are clearly defined are not produced via fracture.
  • Any possible direction can cause a mineral to fracture.
  • The crystal will fracture irregularly rather than along cleavage planes if the interior molecular arrangement is sufficiently complicated that there are no planes of molecules.


Luster is defined as the ability of a mineral to reflect light in a certain way. Depending on how a mineral reflects light, its luster can be identified as metallic or non-metallic.

  • Depending on whether they are opaque or transparent, minerals can be grouped.
  • Every mineral has a distinct sheen, such as smooth, metallic, glossy, etc.


What are Primary Minerals?

Any mineral that was created during the initial crystallization of the host igneous primary rock is referred to as a Primary mineral, and this includes both the primary mineral and any accessory minerals.

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