Intersertal Ferrothoeleiite

Title

Intersertal Ferrothoeleiite

Alternative Title

Ferrotholeiite

Identifier

KBR-8

Description

The intersertal ferrotholeiite samples are highly fractionated and were most likely emplaced before the gabbro of the formation. They have textures associated with rapidly frozen or highly viscous melts. KBR-7 and KBR-9 through KBR-11 are also intersertal ferrotholeiites. Intersertal is a texture marked by the occurrence of interstitial glass between laths of feldspar, usually in basalts. It has an aphanitic- porphyritic texture and holocrystalline. It has a consistent dark gray color with fine veins of quartz <1 mm wide. There are medium grained subhedral plagioclase phenocrysts (2 mm - 5 mm). There is a calcic residue on a heavily oxidized weathered surface. Radiating pyroxene crystals are clearly visible in plain polarized light.
Thin sections are shown in plain and cross polarized light at 40x magnification.
The rock is comprised of 55% plagioclase, 15% pyroxene, 12% biotite, 10% opaques, and 8% olivine.

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

Geolocation