Map of the Ballachulish granite and aureole  Dave Pattison introduces the geological setting, 1994 post-Goldschmidt-Conference excursion. Map extract  Detail of the SW corner of the aureole map, location of the rocks illustrated here. Red colours = intrusion, bands of green shading = contact metamorphic assemblage zones. Outcrop of andalusite-cordierite hornfels  A well-indurated spotted nornfels, but still showing the folded regional metamorphic banding Net-veined hornfels  Fine-grained high-grade hornfels from the inner part of the aureole "Chaotic Zone", innermost aureole  Crumpled and rotated blocks of banded hornfels in partially melted rock adjacent to the igneous contact at the eastern edge of the Complex
Granite - hornfels contact  Contact between outer Ballachulish granite and partially melted hornfels showing veined, disrupted and rotated blocks Granite vein in hornfels  Vertical granite vein (right) cutting net-veined hornfelses of the "Chaotic Zone". DWS225 spotted schist  Poikiloblastic spot in crenulated schist. Spot was most probably of cordierite, now replaced by aggregate of brown sheet silicate. DWS229 cordierite-spotted hornfels  Clusters of thermal biotite; regional fabric is less obvious at this higher grade. Cordierite not obvious in this view. DWS229 cordierite-spotted hornfels  At the centre of the view is a cordierite poikiloblast, almost invisible but for the fact that far fewer muscovite flakes (seen in the outer parts of the view) can be distinguished here. Regional cleavage zone at right has a concentration of thermal biotite and opaques.
DWS229 cordierite-spotted hornfels  Cordierite poikiloblast made visible in light greenish-blue (crossed polars using the sensitive tint plate). It has replaced much of the aluminous matrix minerals but not replaced any of the pre-existing quartz grains. DWS229 cordierite-spotted hornfels  Cordierite poikiloblast in hornfels recognisable from lower concentration of mica flakes in this area. DWS229 cordierite-spotted hornfels  Extent of the cordierite poikiloblast shown by the blue interference colours, crossed polars with sensitive tint plate. DWS230 cordierite-K-feldspar hornfels  A slightly higher-grade rock, here showing a cordierite poikiloblast that apparently nucleated on a cleavage zone and grew outwards (left and right) into the matrix on either side. DWS231 andalusite-cordierite hornfels  A vein, filled almost entirely with andalusite (with moderate relief and showing few inclusions) runs diagonally across the view. Strongly poikiloblastic andalusite (looking like aggregates of separate granules) occurs in the surtrounding matrix with thermal cordierite (indistinguishable from quartz, etc.) and biotite.
DWS231 andalusite-cordierite hornfels  Same view with crossed polars and sensitive tint plate, revealing large single andalusite grains of different orientations making up the vein, and two large cordierite poikiloblasts in the matrix, showing as a yellow patch at upper right, blue patch in lower left corner. DWS231 andalusite-cordierite hornfels  Same area of the slide, showing poikiloblastic andalusite adjacent to the vein, with cordierite to the left. DWS233 corundum-andalusite hornfels  Oval andalusite with poikiloblastic rim at lower right, and highly poikiloblastic andalusite elsewhere surrounding clearer patches. The patches at the left-hand side are cordierite, the others are granoblastic matrix regions (see next photo). No corundum in this view. DWS233 corundum-andalusite hornfels  Same area as previous photo. Shows oval andalusite at lower right, and two twinned cordierite crystals on the left. DWS233 corundum-andalusite hornfels  Detail of the cordierite crystal in the previous view, with crossed polars and sensitive tint plate. The three orientations of the interpenetrant-twinned crystal (a 'trilling') are clearly shown in blue, purple and yellow domains. Note also poikilitic andalusite (yellow) at left.
DWS233 corundum-andalusite hornfels  Association of corundum and andalusite. Corundum (top to lower right) has the highest relief. Silica is no longer in excess: Crd and Kfs have higher SiO2 than the micas they replace, and the remaining muscovite has broken down to corundum + K-feldspar DWS233 corundum-andalusite hornfels  Association of corundum and andalusite. In crossed polars with sensitive tint plate, corundum shows up as bright greenish, andalusite as yellow. DWS235 garnet-cordierite hornfels  Coarse-grained hornfels with evidence for extensive partial melting. Upper part of this view has large K-feldspar crystals with quartz. Lower part contains much cordierite with dark brown biotite. DWS235 garnet-cordierite hornfels  Same view with polars crossed. Upper part probably represent a melt-rich domain, lower part is dominated by fine to medium-grained cordierite aggregates. DWS235 garnet-cordierite hornfels  Small cordierite crystals embedded in quartz. Many of the cordierite crystals show simple twinning. This texture may indicate cordierite crystals permeated by intergranular melt. White mica aggregate in lower right corner is most likely a retrograde replacement of K-feldspar.
DWS235 garnet-cordierite hornfels  As previous, with sensitive tint plate. Small cordierite crystals embedded in quartz. Many of the cordierite crystals show simple twinning. This texture may indicate cordierite crystals permeated by intergranular melt. DWS235 garnet-cordierite hornfels  Part of large garnet poikiloblast, with adjacent matrix of cordierite, biotite, K-feldspar and quartz. DWS235 garnet-cordierite hornfels  Part of large garnet poikiloblast, with adjacent matrix of cordierite, biotite, K-feldspar and quartz. Crossed polars with tint plate. Note variability of cordierite texture, part coarse, part fine aggregates with intergranular quartz or feldspar.