MINERALS

MINERALS

CHEMICAL COMPOSITION -

MOST IMPORTANT ARE SILICATE OR SiO₂-BEARING,

such as

QUARTZ - SiO₂

OLIVINE (Mg,Fe)₂SiO₄

PYROXENE (enstatite) MgSiO₃

FELDSPAR (albite) NaAlSi₃O₈

CAN HAVE RANGE OF COMPOSITIONS -

SOLID SOLUTION: OLIVINE (Mg,Fe)₂SiO₄ CAN RANGE FROM PURE Mg₂SiO₄ TO Fe₂SiO₄

CRYSTAL STRUCTURE -

HOW ATOMS ARE ARRANGED: ATOMS OF APPROPRIATE SIZE CAN FIT INTO PARTICULAR STRUCTURES

PHASE -

DIFFERENT STRUCTURES FOR SAME COMPOSITION DEPENDING ON TEMPERATURE AND PRESSURE