• Question: Are rocks made from all the minerals or is minerals made from rocks

    Asked by BreighLoves HerDog to David, Sarah, Zoe on 20 Nov 2014.
    • Photo: David Foley

      David Foley answered on 20 Nov 2014:

      Minerals are naturally occurring substances formed by geological processes. They have specific physical properties and chemical composition. A rock is a common term for a specific mineral or group of minerals.

      For example, granite rock is made up of the minerals feldspar (KAlSi3O8, NaAlSi3O8, CaAl2Si2O8), quartz (SiO4), mica ( KMg3AlSi3O10(OH)2, KFe3AlSi3O10F2) and amphibole (also SiO4, but in a different geometrical order to quartz).

      Amphibole and quartz have the same chemical formula but because the bonds are arranged in a different order they will look and feel different (have different physical properties). Diamond and graphite are the same – they only contain carbon but one looks good in rings and the other looks good in a pencil!

    • Photo: Sarah Ashwood

      Sarah Ashwood answered on 21 Nov 2014:

      Rocks are generally made from one mineral or a selection of minerals. “Rock” is the generic term for the geological formation where as minerals generally refers to the specific compounds that make up the rock – as David has already discussed a few I won’t go into it in too much detail!

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