Browse Items (296 total)

Adinole was collected from the farm Murrelfontein and occurs above a conspicuous dolerite pegmatite. Adinole is a dense rock of mostly quartz and albite formed as the alteration product of contact metamorphism. It is potassium-rich and has…

Hand Sample: Aphanitic, grayish-white with some patches of fine-grained grey crystals. Weathers to medium yellow-brown.

Hand Sample: Aphanitic grey-black color. Weathers to yellow-tan and orange. Small vesicles present.

Macroscopic: Porphyroblastic amphibole in epidote, chlorite, and garnet calcsilicate rock. This sample represent the metamorphism of calcarious concretions in beds of quartzite to a schist. The formation this samples comes from has considerable…

Rock Sample:
The sample is very dark grey with light grey foliations.
The sample displays thin layering, some areas of chemical weathering, and microfoliations. It is aphanitic. There is quartz- like residue on the outside of the sample. It has…

Rock Sample: The color is a shiny dark grey with a bluish tint. Some parts of the sample are a more dark turquoise. Some faces are lighter and or darker than other faces. There is also a face with a brownish color and another face with a tannish…

Sample contains porphyroblasts of poikilitic hornblende. Thought to represent Na-rich volcanic units.

cummingtonite-poor, brownish-green hornblende dominated

Rock Sample:
The sample is a dark greenish blue with brown layering. On one side of the sample there is a sand-like residue that is tan in color. The sample is aphanitic and possesses micro-folds. The sample appears to have experienced some…

Mica-based schist containing porphyroblasts of andalusite (chiastolite) which have been partly retrograded to muscovite

Mica schist containing coarse (altered) andalusite crystals

Macroscopic: An andalusite, biotite schist with large and abundant garnet porphyroblasts. Low grade of metamorphism. Microscopic: Large andalusite and cordierite phenocrysts within very fine grained matrix. Thin section pictures in XPL unless…

Macroscopic: Andalusite, biotite, garnet, muscovite, chlorite schist. Heavily weathered exterior due to divets and altered nature. High abundance of foliated mica. Microscopic: The andalusite, biotite, and garnet are porphyroblastic with andalusite…

pre-batholith volcanic

Rock Sample:
The color is mainly blue and black. The sample is aphanitic and the cross section of the sample reveals very fined grained phenocrysts (~1mm in diameter). The colors of the phenocrysts range from white, blue, black, or green.
It has…