Browse Items (264 total)

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…

Hand Specimen Pale grey rock, mainly medium to coarse grained quartz sand. Poorly sorted. Small amounts of lithic fragments up to 10 mm across, and shell fragments. Contains <15 vol% clay, making it an arenite.Pale grey cement fizzes…