Browse Items (264 total)

Hand Specimen Fine-grained, greenish black rock comprising dark and white minerals. Contains amygdales, mostly white, though some have black cores. Thin-section Fine-grained plagioclase laths and irregular clinopyroxene…

Hand Specimen Black, porphyritic rock comprising black clinopyroxene, grey feldspar and greenish olivine phenocrysts, in a fine-grained groundmass. Thin-section Plagioclase feldspar - Phenocrysts 1-4mm long, with a…

Hand Specimen Greenish black, coarse-grained rock, comprising olivine, clinopyroxene and plagioclase.Grains typically 1-2 mm across.  Thin-section Olivine - Subhedral to euhedral grains making up ~45% of the rock. Alteration to…

Hand Specimen Sedimentary textures, very poorly sorted. Sub-round to angular grains up to 20mm across. Wide variety of clasts: dark purple, cream, rusty orange, grey, several types of lava. Some black, shiny igneous crystals. Brown-grey…

Hand Specimen Fine-grained, blue-green, sedimentary texture. Slaty cleavage. Some patches of lighter and finer-grained material. Thin-section Slaty cleavage due to the alignment of chlorite and muscovite. Cross-cut by the blobs of the…

Hand Specimen Six vials containing unlithified terrigenous sediments of different grain sizes. These are:   grain size (mm) grain size (phi) Very coarse sand 1-2 -1-0 Coarse sand 0.5-1 0-1 Medium sand 0.25-0.5 1-2 Fine sand 0.125-0.25 2-3 Very fine…

Hand Specimen Very poorly sorted.Angular to sub-angular clasts up to 30 mm long. Randomly orientated. Clasts mainly pale grey, some white, some red. Red-brown colour of the fine-grained matrix indicates iron staining. Matrix and some clasts…

Hand Specimen Poorly sorted. Rounded clasts up to ~15 mm long. Pale yellow matrix of quartz grains. Cement fizzes with acid, indicating that it contains carbonate. This conglomerate is just clast-supported. Thin-section Rounded clasts of very…

Hand Specimen Pale yellow grey rock, almost entirely made up of medium sand quartz grains. These are sub-rounded, very well sorted, and are held together by a matrix of siliceous silt. Contains a significant amount of clay, but <15 vol%,…

Hand Specimen Reddish brown rock made up of pinkish feldspar, colourless quartz, and some dark grey grains. Medium to coarse sand. Moderately rounded. Fairly well sorted. Contains <15 vol% clay, so this is an arenite. No fizzing with…