Trace elements and mineral chemistry of silicified wood from Thailand: colours and elemental distribution. Issue 7 (2nd October 2016)

• Record Type: Journal Article
• Authors: Saminpanya, S.
• Is Part Of: Australian journal of earth sciences. Volume 63:Issue 7(2016)
• Page Start: 873
• Page End: 884
• Publication Date: 2016-10-02
• Subjects: Silicified wood -- trace elements -- EPMA -- geochemical characteristic -- colour -- Thailand; Earth sciences -- Australia -- Periodicals; Earth sciences -- Periodicals; Geology -- Australia -- Periodicals; Geology -- Periodicals; 559.405
• DOI: 10.1080/08120099.2016.1251492
• Languages: English
• ISSNs: 0812-0099

Abstract

ABSTRACT: Thai silicified woods were examined using electron probe microanalysis, yielding chemical data that characterised the samples into two groups: low and high silica contents (82—94 wt% and 94—98 wt%). The elements analysed in order of abundance include Si > Fe > Ca > Na > Al > Ti > K > Mg > Mn > Zr. Iron plays a major role in the colour range (red, orange, yellow, brown, grey and black) of the samples. Calcium is associated with Fe in the darker colours of the wood. Pseudo-crystallochemistry has been used for the substitution of trace elements for Si 4+ in silica polymorphs. The atomic channels that run parallel to the c-axis of silica polymorphs or lattice defects, or even the charge balance for trivalent-ion substitution for Si 4+, can accommodate monovalent ions (K + and Na + ). Vacant and atomic cavities, which are charged balanced by trivalent ions [Al 3+ or Fe 3+ substituting for Si 4+ ], are commonly occupied by divalent ions (Ca 2+, Mg 2+ and Mn 2+ ). Quadrivalent ions, Ti 4+ and Zr 4+ are non-structurally incorporated but form clusters of mineral inclusions in the samples. Several other trace-element contents are also in the form of mineral/fluid inclusions hosted in the woods.