A magnesium analogue of chalcophanite in manganese-rich concretions
from Baja California
Russel M. Potter and
George R. Rossman
Division of Geological and Planetary
Sciences
California Institute of Technoogy
Pasadena, CA 91125
Abstract
Concretions which carry chemical remanent magnetization in sediments in
Baja Califor nia, Mexico, previously called "hydropsilomelane," were
found to consist of siltstone matrix minerals cemented by a manganese
oxide. The X-ray powder pattern, infrared spectra, and chemical
analyses indicate that the manganese oxide has the chalcophanite
structure. The high concentration of magnesium, presumed to occur in
the interlayer position of this min eral, suggests that it is the
magnesium analogue of chalcophanite and extends the known
range of substitution in chalcophanite-structure minerals.
last updated: 5-Oct-2020