A high-aluminous chlorite-swelling chlorite regular mixed-layer clay mineral

Abstract

A B ST R A C T: One of the alteration products of a deuteric altered beryl is a highaluminous chlorite-swelling chlorite regular mixed-layer clay mineral. An attempt was made to calculate the structural formula, and the results of X-ray, differential thermal and electron diffraction analyses are given.During an investigation of the alteration products of beryl from the Dernburg pegmatite, Karibib, South West Africa (Roering & Heckroodt, 1964), a mineral with a 30 A spacing was detected in the fine fraction. The responses of reflections, attributed to this mineral, to treatment with organic liquids indicated that the mineral is of an expanding lattice type. The fine fraction was subsequently beneficiated in an attempt to obtain a pure sample for a detailed investigation.The altered beryl occurs in a pegmatite located in quartzites of the Damara System. It has been mined for beryl, amblygonite, and tantalite. Replacement bodies consisting of lithium-bearing mica and albite also occur, with or without cleavelandite-rich borders. The altered beryl occurs where these cleavelandite-rich borders abut against the beryl in the central zone of the pegmatite. From field relationships it would appear that this alteration was caused by deuteric pegmatite solutions intimately associated with the formation of the lithium mica-bearing replacement zones and their cleavelandite-rich margins. PREPARATION OF SAMPLETwo small specimens of highly altered beryl were crushed in an iron pestle and mortar, and any contaminating iron was removed by means of a strong magnet. The crushed sample was dispersed in a 'Waring Blendor' for 20 min to facilitate the separation of the clay particles adhering to other mineral grains and to disintegrate the clay aggregates. The fraction less than 5 t~ was then obtained by sedimentation methods. The water of sedimentation was removed by means of a membrane filter.

Regularly Interstratified Chlorite—Dioctahedral Smectite in Dike-Intruded Shales, Montana

“…Corrensite has been observed also in argillaceous siltstone (Earley, Bradley, McVeagh and Vanden Heuval, 1956); as a hydrothermal alteration product of andesitic and chloritic rocks (Harvey and Beck, 1960); as an alteration product of a deutericly altered beryl (Heckroodt and Roering, 1965); in metalimestones (Wilson and Bain, 1970) and in hydrothermal deposits (Sudo, Takahashi and Matsui, 1954).…”

Nickel Containing Regularly Interstratified Chlorite-Saponite from Szklary, Lower Silesia, Poland

“…The interstratification of expanding chlorite and nonexpanding chlorite layers has been described by Lippmann (1954) and independently by MartinVivaldi and MacEwan 0960) under the name of corrensite. Heckroodt and Roering (1965) described interstratification of high aluminous expanding and nonexpanding chlorite layers.…”