Title
Porphyroblastic Metasediments
Alternative Title
Hybrid rock
Identifier
KBR-14
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 13 to note this range. This sample is medium grained, holocrystalline, and has a hypidiomorphic-granular texture. It has dark gray crystals, ranging from < 1 mm- 3 mm. Dramatic labradorite-like striations cover about half of the rock. Groups of striations are roughly at right angles to one another. The rusty looking weathered surface is more vibrant on this rock (than the other samples).
The thin sections shown in plain polarized Light and cross polarized light at 40x magnification.
The rock is 60% plagioclase, 40% pyroxenes (mainly enstatite), and <1% opaques.
The thin sections shown in plain polarized Light and cross polarized light at 40x magnification.
The rock is 60% plagioclase, 40% pyroxenes (mainly enstatite), and <1% 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