Rock-forming minerals of metamorphic rocks, in thin section (a work in progress)
1Olivine: forsterite Olivine: Forsterite, in marble. Plane-polarised light, width of view 2.5 mm.
2Olivine: forsterite Olivine: Forsterite, in marble. Polars crossed, width of view 2.5 mm.
3Zircon Zircon, with distinct core and rim zones, in aluminous granulite. Plane-polarised light, width of view 0.25 mm.
4Zircon Zircon, with distinct core and rim zones, in aluminous granulite. Polars crossed, width of view 0.25 mm.
5Titanite Titanite (sphene), in calc-silicate marble. Plane-polarised light, width of view 1 mm.
6Titanite Titanite (sphene), in calc-silicate marble. Polars crossed, width of view 1 mm.
7Garnet: almandine Garnet: almandine, in kyanite-grade mica schist. Plane-polarised light, width of view 2.5 mm.
8Garnet: almandine Garnet: almandine, idioblastic and poikiloblastic, in schist. Plane-polarised light, width of view 6 mm.
9Garnet: almandine Garnet: almandine, with graphitic inclusion trails showing a deflection near the rim, in kyanite-garnet schist. Plane-polarised light, width of view 1 mm.
10Garnet: almandine Garnet: almandine, with rotational double-spiral inclusion trails, in schist. Plane-polarised light, width of view 2.5 mm.
11Garnet: almandine-pyrope Garnet: almandine-pyrope, with sillimanite inclusions, in granulite-facies garnet-cordierite gneiss. Plane-polarised light, field of view 5 mm
12Garnet: almandine-pyrope-grossular Garnet: almandine-pyrope-grossular, with corona texture of plagioclase and orthopyroxene, in granulite-facies metabasite. Plane-polarised light, field of view 4 mm
13Garnet: almandine-pyrope-grossular Garnet: almandine-pyrope-grossular (isotropic mass at centre), with corona texture of plagioclase and orthopyroxene, in granulite-facies metabasite. Polars crossed, field of view 4 mm
14Garnet: andradite Garnet: andradite, in marble. Plane-polarised light, field of view 3.5 mm
15Vesuvianite Vesuvianite, in calc-silicate skarn. Plane-polarised light, field of view 2.5 mm
16Vesuvianite Vesuvianite, in calc-silicate skarn. Polars crossed, field of view 2.5 mm
17Sillimanite Sillimanite (fibrolite), intergrown with biotite in schist. Plane-polarised light, field of view 5 mm
18Sillimanite Sillimanite (fibrolite), intergrown with biotite in schist. Polars crossed, field of view 5 mm
19Sillimanite Sillimanite, nodules of fibrolite in schist. Plane-polarised light, field of view 5 mm
20Sillimanite Sillimanite, nodules of fibrolite in schist. Polars crossed, field of view 5 mm
21Sillimanite Sillimanite, prismatic, in aluminous granulite. Plane-polarised light, field of view 2.5 mm
22Sillimanite Sillimanite, prismatic, in aluminous granulite. Polars crossed, field of view 2.5 mm
23Andalusite Andalusite (chiastolite) in graphitic hornfels. Plane-polarised light, field of view 8 mm
24Andalusite Andalusite (chiastolite) with pink core zone, in graphitic hornfels. Plane-polarised light, field of view 2.5 mm
25Andalusite Andalusite, poikiloblastic, in schist. Ordinary light, field of view 10 mm
26Kyanite Kyanite, in schist. Plane-polarised light, field of view 2.5 mm
27Kyanite Kyanite, in schist, showing three different crystal orientations. Plane-polarised light, field of view 2.5 mm
28Kyanite Kyanite, in schist, showing three different crystal orientations. Polars crossed, field of view 2.5 mm
29Staurolite Staurolite, prism in schist. Plane-polarised light, field of view 2.5 mm
30Staurolite Staurolite poikiloblast, in schist. Plane-polarised light, field of view 2.5 mm
31Staurolite Staurolite poikiloblast showing interpenetrant twinning, in schist. Polars crossed, field of view 2.5 mm
32Staurolite Staurolite showing internal inclusion fabric, in schist. Plane-polarised light, field of view 1 mm
33Staurolite Staurolite poikiloblast, in hornfels. Plane-polarised light, field of view 2 mm
34Staurolite Staurolite poikiloblast, in hornfels. Polars crossed, field of view 2 mm
35Chloritoid Chloritoid, in schist. Plane-polarised light, field of view 2 mm
36Chloritoid Chloritoid, in schist. Plane-polarised light, field of view 2.5 mm
37Chloritoid Chloritoid, in schist, showing lamellar twinning and anomalous interference colours. Polars crossed, field of view 2.5 mm
38Sapphirine Sapphirine (blue), with spinel, phlogopite and enstatite in Mg-Al-rich granulite. Plane-polarised light, field of view 2.5 mm
39Clinozoisite Epidote group: Clinozoisite, showing anomalous interference colours. Polars crossed, field of view 1 mm
40Clinozoisite Epidote group: Clinozoisite, poikiloblast in eclogite. Plane-polarised light, field of view 2.5 mm
41Clinozoisite Epidote group: Clinozoisite, poikiloblast in eclogite, showing zoned birefringence (core more Fe-rich). Polars crossed, field of view 2.5 mm
42Epidote Epidote in calc-silicate marble. Plane-polarised light, field of view 2.5 mm
43Epidote Epidote in calc-silicate marble. Polars crossed, field of view 2.5 mm
44Zoisite Epidote group: Zoisite, in high-pressure gneiss. Plane-polarised light, field of view 1.25 mm
45Zoisite Epidote group: Zoisite, showing anomalous blue interference colours and narrow rim of clinozoisite. Polars crossed, field of view 1.25 mm
46Piemontite Epidote group: Piemontite, in manganiferous metachert. Plane-polarised light, field of view 1 mm
47Piemontite Epidote group: Piemontite, in manganiferous metachert. Polars crossed, field of view 1 mm
48Lawsonite Lawsonite, pale brownish, with glaucophane, chlorite and white mica, in blueschist. Plane-polarised light, field of view 1 mm
49Lawsonite Lawsonite, in blueschist. Polars crossed, field of view 1 mm
50Cordierite Cordierite, granoblastic-polygonal texture, granulite facies. Polars crossed, field of view 5 mm
51Cordierite Cordierite, poikiloblastic, in low-P spotted schist (Buchan type). Plane-polarised light, field of view 5 mm
52Cordierite Cordierite, poikiloblastic, in low-P spotted schist (Buchan type). Polars crossed, field of view 5 mm
53Cordierite Cordierite, showing complex sector twinning, in spotted hornfels. Polars crossed, field of view 2.5 mm
54Cordierite Cordierite (colourless), in aluminous hornfels. Plane-polarised light, field of view 2.5 mm
55Cordierite Cordierite, in aluminous hornfels. Polars crossed, field of view 2.5 mm
56Cordierite Cordierite, with sillimanite inclusions, in granulite-facies metapelitic gneiss. Plane-polarised light, field of view 5 mm
57Cordierite Cordierite, with sillimanite inclusions, in granulite-facies metapelitic gneiss. Polars crossed, field of view 5 mm
58Osumilite Osumilite (double-ring silicate resembling cordierite, diagnostic of ultrahigh-T metamorphism), with feldspar and orthopyroxene. Note yellow 'pinite' alteration. Plane-polarised light, field of view 2.5 mm
59Osumilite Osumilite (double-ring silicate resembling cordierite, diagnostic of ultrahigh-T metamorphism), with feldspar and orthopyroxene. Note near-isotropic 'pinite' alteration at margins. Polars crossed, field of view 2.5 mm
60Clino- and Orthopyroxene Pyroxene: clinopyroxene (green) and orthopyroxene (pink) in granulite-facies tonalitic gneiss. Plane-polarised light, field of view 5 mm
61Clino- and Orthopyroxene Pyroxene: clinopyroxene (mostly second-order colours) and orthopyroxene (first-order colours) in granulite-facies tonalitic gneiss. Polars crossed, field of view 5 mm
62Clinopyroxene Pyroxene: clinopyroxene (diopside/augite), showing exsolution lamellae, in granulite-facies metabasite. Polars crossed, field of view 5 mm
63Diopside Pyroxene: diopside, in calc-silicate marble. Plane-polarised light, field of view 1 mm
64Diopside Pyroxene: diopside, in calc-silicate marble. Polars crossed, field of view 1 mm
65Enstatite Pyroxene: enstatite (pale pinks and greens) with olivine (colourless, upper right) and pale olive hornblende, in granulite-facies ultrabasic gneiss. Plane-polarised light, field of view 5 mm
66Enstatite Pyroxene: enstatite (first-order colours) with olivine (high colours, upper right), in granulite-facies ultrabasic gneiss. Polars crossed, field of view 5 mm
67Enstatite Pyroxene: aluminous enstatite, poikiloblast in granulite-facies cordierite gneiss. Plane-polarised light, width of view 19 mm
68Jadeite Pyroxene: jadeite (altered at rim and in fractures) in eclogite-facies meta-granite. Plane-polarised light, field of view 2.5 mm
69Jadeite Pyroxene: jadeite (altered at rim and in fractures) in eclogite-facies meta-granite. Polars crossed, field of view 2.5 mm
70Omphacite Pyroxene: omphacite, with symplectitic reaction rim, in eclogite. Plane-polarised light, field of view 1.5 mm
71Omphacite Pyroxene: omphacite, with symplectitic reaction rim, in eclogite. Polars crossed, field of view 1.5 mm
72Omphacite Pyroxene: omphacite, aggregate of crystals, with garnet, white mica and glaucophane in eclogite. Plane-polarised light, field of view 2.5 mm
73Omphacite Pyroxene: omphacite, aggregate of crystals, with garnet, white mica and glaucophane in eclogite. Polars crossed, field of view 2.5 mm
74Wollastonite Wollastonite, showing three cleavages on basal section. Plane-polarised light, field of view 2.5 mm
75Wollastonite Wollastonite, showing three cleavages and high birefringence on basal section. Polars crossed, field of view 2.5 mm
76Tremolite Amphibole: tremolite in marble. Plane-polarised light, field of view 2.5 mm
77Tremolite Amphibole: tremolite in marble. Polars crossed, field of view 2.5 mm
78Actinolite Amphibole: actinolite (pale green) as core of composite crystal surrounded by triple-chain silicate, in ultrabasic gneiss. Plane-polarised light, field of view 1.5 mm
79Actinolite Amphibole: actinolite (magenta interference colour) as core of composite crystal surrounded by triple-chain silicate (blue), in ultrabasic gneiss. Polars crossed, field of view 1.5 mm
80Hornblende Amphibole: blue-green hornblende, in various orientations showing different pleochroism colours, in garnet-grade metagabbro. Plane-polarised light, field of view 4 mm
81Hornblende Amphibole: blue-green hornblende, in garnet-grade metagabbro. Note low-order interference colours, partly masked by body colour. Polars crossed, field of view 4 mm
82Hornblende Amphibole: hornblende, in foliated amphibolite. Plane-polarised light, field of view 2 mm
83Hornblende Amphibole: hornblende, in amphibolite derived from gabbro. Plane-polarised light, field of view 2 mm
84Hornblende Amphibole: brown hornblende in high-temperature amphibolite. Note greenish rims resulting from retrograde change. Plane-polarised light, field of view 4 mm
85Anthophyllite Amphibole: anthophyllite, in contact-metamorphosed rock. Plane-polarised light, field of view 2 mm
86Anthophyllite Amphibole: anthophyllite, in contact-metamorphosed rock. Polars crossed, field of view 2 mm
87Gedrite Amphibole: gedrite (Na-Al anthophyllite), in cordierite-gedrite gneiss. Plane-polarised light, field of view 6 mm
88Gedrite Amphibole: gedrite (Na-Al anthophyllite), in cordierite-gedrite gneiss. Polars crossed, field of view 6 mm
89Glaucophane Amphibole: glaucophane, in blueschist. Plane-polarised light, prisms parallel to polariser. Plane-polarised light, field of view 2.5 mm
90Glaucophane Amphibole: glaucophane, in blueschist. Plane-polarised light, prisms normal to polariser. Plane-polarised light, field of view 2.5 mm
91Glaucophane (crossite) Amphibole: crossite (glaucophane with Fe3+), in blueschist. Plane-polarised light, field of view 2.5 mm
92Glaucophane (crossite) Amphibole: crossite (glaucophane with Fe3+), in metachert. Plane-polarised light, field of view 2.5 mm
93Glaucophane (crossite) Amphibole: crossite (glaucophane with Fe3+), in metachert. Polars crossed, field of view 2.5 mm
94Muscovite Muscovite (colourless), with biotite, garnet and kyanite in schist. Plane-polarised light, field of view 6 mm
95Muscovite Muscovite (bright colours), with biotite, garnet and kyanite in schist. Polars crossed, field of view 6 mm
96Muscovite Muscovite, in phyllite. Polars crossed, field of view 2.5 mm
97Muscovite Muscovite (randomly-oriented crystals) in aluminous granofels. Polars crossed, field of view 2.5 mm
98Muscovite (phengite) Muscovite var. phengite, three grains in different orientations, in eclogite. Plane-polarised light, field of view 1 mm
99Muscovite (phengite) Muscovite var. phengite, three grains in different orientations, in eclogite. Central grain will give a uniaxial figure (3T polytype). Polars crossed, field of view 1 mm
100Biotite Biotite, poikiloblast in biotite-grade schist (greenschist facies). Plane-polarised light, field of view 2 mm
101Biotite Biotite, in high-grade gneiss with cordierite and quartz. Plane-polarised light, field of view 2.5 mm
102Biotite Biotite, in high-grade gneiss with cordierite and quartz. Polars crossed, field of view 2.5 mm
103Phlogopite Phlogopite (almost colourless) with calcite and forsterite in marble. Plane-polarised light, field of view 2.5 mm
104Phlogopite Phlogopite, with calcite and forsterite in marble. Polars crossed, field of view 2.5 mm
105Stilpnomelane Stilpnomelane (brown), in metabasic greenschist. Plane-polarised light, field of view 1 mm
106Stilpnomelane Stilpnomelane (brown, high birefringence), in metabasic greenschist. Polars crossed, field of view 1 mm
107Talc Talc, in metasomatised peridotite. Polars crossed, field of view 3.5 mm
108Chlorite Chlorite, cluster of green flakes in polymetamorphic gneiss. Plane-polarised light, field of view 3.5 mm
109Chlorite Chlorite, microfolded aggregate with albite and epidote in greenschist. Plane-polarised light, field of view 1.5 mm
110Chlorite Chlorite, microfolded aggregate with albite and epidote in greenschist. Note purplish-brown anomalous interference colour. Polars crossed, field of view 1.5 mm
111Chlorite Chlorite, colourless Mg-chlorite with spinel, in forsterite marble. Plane-polarised light, field of view 2 mm
112Chlorite Chlorite, Mg-chlorite with spinel, in forsterite marble. Note bright first-order white interference colour. Polars crossed, field of view 2 mm
113Serpentine Serpentine, replacing forsterite in marble. Plane-polarised light, field of view 2.5 mm
114Serpentine Serpentine, replacing forsterite in marble. Polars crossed, field of view 2.5 mm
115Prehnite Prehnite, radiating birefringent blades filling an alteration vein in amphibolite. Polars crossed, field of view 1.5 mm
116Feldspar: Albite Albite, porphyroblast with graphitic inclusion trails in low-grade mica schist. Polars crossed, field of view 2.5 mm
117Feldspar: Albite Albite, poikiloblast in metabasic greenschist. Plane-polarised light, field of view 1 mm
118Feldspar: Albite Albite, poikiloblast in metabasic greenschist. Polars crossed, field of view 1 mm
119Feldspar: Microcline Microcline (low relief), in calc-silicate marble with calcite and epidote. Plane-polarised light, field of view 1 mm
120Feldspar: Microcline Microcline (with 'tartan' twinning), in calc-silicate marble with calcite and epidote. Polars crossed, field of view 1 mm
121Quartz Quartz, granoblastic aggregate with muscovite in siliceous schist. Polars crossed, field of view 2.5 mm
122Quartz Quartz, partly recrystallised vein stringer in schist, Polars crossed, field of view 5 mm
123Coesite Coesite, with reaction rim of quartz, as inclusion in omphacite. Plane-polarised light, field of view 0.8 mm
124Coesite Coesite, with reaction rim of quartz, as inclusion in omphacite. Polars crossed, field of view 0.8 mm
125Corundum Corundum, with reaction rims of spinel (green), sapphirine (blue) and kornerupine (pale grey-blue) in aluminous phlogopite gneiss. Plane-polarised light, field of view 6 mm
126Corundum Corundum (first-order pale yellow), with reaction rims of spinel (isotropic), sapphirine and kornerupine (both low-order grey) in aluminous phlogopite gneiss. Polars crossed, field of view 6 mm
127Rutile Rutile, large grain in metabasic eclogite. Plane-polarised light, field of view 1 mm
128Spinel Spinel (sensu stricto, i.e. Mg-Al spinel) in marble, with partial alteration to Mg-chlorite. Plane-polarised light, field of view 2 mm
129Spinel Spinel (sensu stricto, i.e. Mg-Al spinel), isotropic, in marble, with partial alteration to Mg-chlorite (white). Polars crossed, field of view 2 mm
130Spinel: Hercynite Hercynite (green Fe-Al spinel) with fine internal precipitate of opaque magnetite and reaction rims of cordierite and garnet, in ultrahigh temperature metapelitic gneiss. Plane-polarised light, field of view 1 mm
131Brucite Brucite, pseudomorphs after periclase, in contact-metamorphosed marble. Plane-polarised light, field of view 1.3 mm
132Brucite Brucite, pseudomorphs after periclase, in contact-metamorphosed marble. Polars crossed, field of view 1.3 mm
133Calcite Calcite, with narrow twin lamellae, in marble. Plane-polarised light, field of view 1 mm
134Calcite Calcite, with very high interference colours and showing narrow twin lamellae, in marble. Polars crossed, field of view 1 mm
135Dolomite Dolomite, in high-pressure schist. Plane-polarised light, field of view 2.5 mm
136Dolomite Dolomite, in high-pressure schist. Polars crossed, field of view 2.5 mm
137Magnesite Magnesite, in magnesite-talc rock (metasomatised peridotite). Plane-polarised light, field of view 3.5 mm
138Magnesite Magnesite, in magnesite-talc rock (metasomatised peridotite). Polars crossed, field of view 3.5 mm
The sequence of minerals here follows that of Deer, Howie & Zussman, i.e. ortho- and ring silicates first, followed by chain silicates, sheet silicates, framework silicates, and finally non-silicates. The search facility will find words in image titles and descriptions.