Title
Porphyroblastic Metasediments
Alternative Title
Hybrid rock
Identifier
KBR-13
Description
The porphyroblastic metasediments/hybrid rocks were interpreted by Eales and his co-workers to be metamorphosed "Red Beds" Formation sediments but could be magmatic in origin. The samples illustrate the range in textures; see KBR 12 and KBR 14 to note this range. This sample has an aphanitic- porphyritic texture and is holocrystalline. There is a light gray anhedral ground mass and medium-grained phenocrysts (1 mm- 3 mm).There are fine, snaky veins of reddish material on the fresh surface. Minor euhedral phenocrysts of plagioclase with reaction rims (4 mm).
The thin sections shown in plain polarized light and cross polarized light at 40x magnification.
The rock is 40% plagioclase, 20% pyroxenes (Enstatite), and 20% opaques.
The thin sections shown in plain polarized light and cross polarized light at 40x magnification.
The rock is 40% plagioclase, 20% pyroxenes (Enstatite), and 20% opaques.
Date
No date given.
Contributor
Western Minerals, Inc.
Is Part Of
http://www.geosciencecollections.milne-library.org/collections/show/17
Spatial Coverage
Karoo- Birds River, Eastern Cape, South Africa
Temporal Coverage
183-179 Ma (Jurassic)
Accrual Method
Purchased from Western Minerals, Inc.
Unit
Lesotho Formation
Number of Thin Sections
1