A Practical Introduction to Optical Mineralogy

1 Introduction to the microscopic study of minerals.- 1.1 Introduction.- 1.2 The transmitted-light microscope.- 1.3 Systematic description of minerals in thin section using transmitted light.- 1.3.1 Properties in plane polarised light.- 1.3.2 Properties under crossed polars.- 1.4 The reflected-light microscope.- 1.5 The appearance of polished sections under the reflected-light microscope.- 1.6 Systematic description of minerals in polished section using reflected light.- 1.6.1 Properties observed using plane polarized light (PPL).- 1.6.2 Properties observed using crossed polars.- 1.6.3 The external nature of grains.- 1.6.4 Internal properties of grains.- 1.6.5 Vickers hardness number (VHN).- 1.6.6 Distinguishing features.- 1.7 Observations using oil immersion in reflected-light studies.- 1.8 Polishing hardness.- 1.9 Microhardness (VHN).- 1.10 Points on the use of the microscope (transmitted and reflected light).- 1.11 Thin- and polished-section preparation.- 2 Silicate minerals.- 2.1 Crystal chemistry of silicate minerals.- 2.2 Mineral descriptions.- Al2SiO5 polymorphs 35; Amphibole group 41; Beryl 56; Chlorite 57; Chloritoid 58; Clay minerals 59; Cordierite 61; Epidote group 63; Feldspar group 67; Feldspathoid family 84; Garnet group 87; Humite group 88; Mica group 90; Olivine group 95; Pumpellyite 98; Pyroxene group 99; Scapolite 117; Serpentine 119; Silica group 120; Sphene 124; Staurolite 125; Talc 126; Topaz 127; Tourmaline group 128; Vesuvianite 129; Zeolite group 129; Zircon 131.- 3 The non-silicates.- 3.1 Introduction.- 3.2 Carbonates.- 3.3 Sulphides.- 3.4 Oxides.- 3.5 Halides.- 3.6 Hydroxides.- 3.7 Sulphates.- 3.8 Phosphate.- 3.9 Tungstate.- 3.10 Arsenide.- 3.11 Native elements.- 4 Transmitted-light crystallography.- 4.1 Polarised light: an introduction.- 4.2 Refractive index.- 4.3 Isotropy.- 4.4 The biaxial indicatrix triaxial ellipsoid.- 4.5 The uniaxial indicatrix.- 4.6 Interference colours and Newton's Scale.- 4.7 Fast and slow components, and order determination.- 4.7.1 Fast and slow components.- 4.7.2 Quartz wedge and first order red accessory plate.- 4.7.3 Determination of order of colour.- 4.7.4 Abnormal or anomalous interference colours.- 4.8 Interference figures.- 4.8.1 Biaxial minerals.- 4.8.2 Sign determination for biaxial minerals.- 4.8.3 Flash figures.- 4.8.4 Uniaxial minerals.- 4.8.5 Isotropic minerals.- 4.9 Pleochroic scheme.- 4.9.1 Uniaxial minerals.- 4.9.2 Biaxial minerals.- 4.10 Extinction angle.- 5 Reflected-light theory.- 5.1 Introduction page.- 5.1.1 Reflectance.- 5.1.2 Indicating surfaces of reflectance.- 5.1.3 Observing the effects of crystallographic orientation on reflectance.- 5.1.4 Identification of minerals using reflectance measurements.- 5.2 Colour of minerals in PPL.- 5.2.1 CIE (1931) colour diagram.- 5.2.2 Exercise on quantitative colour values.- 5.3 Isotropic and anisotropic sections.- 5.3.1 Isotropic sections.- 5.3.2 Anisotropic sections.- 5.3.3 Polarisation colours.- 5.3.4 Exercise on rotation after reflection.- 5.3.5 Detailed observation of anisotropy.- Appendix A.1 Refractive indices of biaxial minerals.- Appendix A.2 Refractive indices of uniaxial positive minerals.- Appendix A.3 Refractive indices of uniaxial negative minerals.- Appendix A.4 Refractive indices of isotropic minerals.- Appendix C Properties of ore minerals.- Appendix D Mineral identification chart.- Appendix E Gangue minerals.