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Cathodoluminescence microscopy of myrmekite

R. Forrest Hopson and Karl Ramseyer
Cathodoluminescence microscopy of myrmekite
Geology (Boulder) (April 1990) 18 (4): 336-339


Rim, wartlike, and isolated myrmekite are the three types of myrmekite that occur in the Rubidoux Mountain leucogranite. Combined cathodoluminescence, scanning electron microscopy, and electron microprobe investigations suggest that myrmekite is the product of K-feldspar and plagioclase replacement. Clusters of optically continuous quartz vermicules are interconnected, exhibiting a dendroid shape. The surrounding myrmekitic plagioclase is chemically undistinguishable from the host bluish-luminescing plagioclase with a mean composition of Ab (sub 0.81) An (sub 0.18) Kf (sub 0.01) . Only the fractured cores of some plagioclase grains, which display yellowish luminescence, represent a plagioclase with a higher An content (An (sub 0.59) Ab (sub 0.39) Kf (sub 0.2) ). Petrographic evidence shows that myrmekite is a complex reaction, where the main phase formed prior to exsolution of albite from K-feldspar and crystallization of albitic rims. The formation of myrmekite is therefore a reaction occurring during late-stage magmatic crystallization.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 18
Serial Issue: 4
Title: Cathodoluminescence microscopy of myrmekite
Affiliation: 6597 Camino Venturoso, Goleta, CA, United States
Pages: 336-339
Published: 199004
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 17
Accession Number: 1990-033759
Categories: Mineralogy of silicatesIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N33°58'60" - N33°58'60", W117°22'00" - W117°22'00"
Secondary Affiliation: Univ. Bern, CHE, Switzerland
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1990
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