The nature of opal I. nomenclature and constituent phases
作者:
J. B. Jones,
E. R. Segnit,
期刊:
Journal of the Geological Society of Australia
(Taylor Available online 1971)
卷期:
Volume 18,
issue 1
页码: 57-68
ISSN:0016-7614
年代: 1971
DOI:10.1080/00167617108728743
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Natural hydrous silicas may be subdivided into three well‐defined structural groups—opal‐C (well‐ordered α‐cristobalite), opal‐CT (disordered a‐cristobalite, a‐tridymite) and opal‐A (highly disordered, near amorphous). Lussatite from the original locality is identical with opal‐CT and thus appears to be a legitimate term for this class of opal. Although the prime criterion used is the nature of the X‐ray diffraction pattern, supplementary information from infra‐red absorption, dilatometer and thermal techniques supports the three‐fold classification.
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