Cordierite in spotted hornfels High-grade biotite hornfels High grade cordierite--K-feldspar hornfels High grade cordierite--K-feldspar hornfels High grade cordierite--biotite-spinel hornfels
High grade cordierite--biotite-spinel hornfels High grade metabasic pyroxene hornfels High grade metabasic pyroxene hornfels Hornfelsed lava, transitional to pyroxene hornfels texture SW England Hornfelses
SW England hornfelses - pelitic SW England hornfelses - pelitic SW England hornfelses - pelitic SW England hornfelses - pelitic SW England hornfelses - pelitic  Hornfelsed slate with large cordierite spots, altered to sericite around their rims. An intruded felsic vein runs along the lower edge of the image. The dark red of the biotite suggests a high Ti content and high temperature achieved at the granite contact. Sample 25H from Tater-Du, at the southern edge of the Land's End granite.
SW England hornfelses - pelitic SW England hornfelses - pelitic  Andalusite-biotite hornfels, sample 7P, from Cape Cornwall (Land's End granite aureole). SW England hornfelses - pelitic  Sample 27A, from the aureole of the Tregonning granite at Lesceave Rocks, Praa Sands, Cornwall. Well preserved microstructure inherited from regional deformation, no porphyroblasts, but note the deep orange-red (Ti-rich) post-tectonic thermal biotite. SW England hornfelses - mafic  Biotite-rich hornfels probably derived from a hydrothermally altered mafic rock. Priest's Cove, Cape Cornwall. Note the deformed felsic vein at the left of the image. SW England hornfelses - mafic  Amphibole-rich metabasic hornfels from Botallack, near St Just, Land's End aureole, sample 14P.
SW England hornfelses - cordierite-anthophyllite  One of the famous cordierite-anthophyllite hornfelses of Cape Kenidjack, near St Just, Land's End granite aureole, specimen 12D. Clear round patches are cordierite, set in brown biotite/phlogopite. Anthophyllite forms radiating clusters of narrow prisms, visible with difficulty at this scale. SW England hornfelses - cordierite-anthophyllite  Specimen 10A cordierite-anthophyllite hornfels. Similar to 12D, but with cm-sized cordierite patches in a matrix of brown biotite/phlogopite and anthophyllite. SW England hornfelses - calc-silicate (skarn)  A coarse-grained rock made almost entirely of Ca-rich garnet, showing concentric growth zoning. Sample 16B, from Botallack, near St Just. SW England hornfelses - calc-silicate (skarn)  A coarse-grained rock consisting of grossular-rich garnet (rounded crystals), vesuvianite (tabular crystals) and opaque oxide(s) (magnetite, ilmenite). Sample 16B, from Botallack, near St Just. Sanidinite Facies
Calc-silicate xenolith in Bushveld Complex  Banded green/white xenolithic block enclosed in the Critical Zone of the mafic layered series. Contains Ca-Mg minerals monticellite, akermanite (melilite group), diopside, forsterite, spinel. Sanidinite facies: Bushveld complex xenolith  The dominant colourless mineral in this rock is monticellite (CaMgSiO4), forming a near-equilibrium polygonal texture. This xenolith was immersed in the Critical Zone of the mafic layered series at about 1300°C. Sanidinite facies: Bushveld complex xenolith  The dominant low-birefringent mineral in this rock is monticellite (CaMgSiO4), forming a near-equilibrium polygonal texture. This xenolith was immersed in the Critical Zone of the mafic layered series at about 1300°C. Sanidinite facies: Rum - partially melted Lewisian gneiss  Melting has occurred along grain boundaries in the gneiss. The melt crystallised to needle-shaped crystals of tridymite embedded in feldspar. The tridymite has since inverted to quartz, but retains the high-temperature crystal habit. Sanidinite facies: Rum - partially melted Torridonian sandstone  A crystallised melt pool among clasts in this thermally metamorphosed arkosic sandstone contains abundant semi-radiating crystals of quartz replacing tridymite. Specimen 13081 (AC Dunham's D62)
Sanidinite facies: Rum - partially melted Torridonian sandstone  A crystallised melt pool in this thermally metamorphosed arkosic sandstone contains radiating crystals of quartz replacing tridymite. In many cases these are arranged around resorbed relics of quartz from the original rock. Specimen 13081 (AC Dunham's D62) Sanidinite facies: Rum - partially melted Torridonian sandstone  A crystallised melt pool in this thermally metamorphosed arkosic sandstone contains radiating crystals of quartz replacing tridymite. In many cases these are arranged around resorbed relics of quartz from the original rock. Specimen 13081 (AC Dunham's D62), crossed polars.