Table T4. Minerals identified by XRD analysis, Site 1191.

Table T4. Minerals identified by XRD analysis, Site 1191.

Core, section,
interval (cm)

Unit

Description

XRD identification:
major (minor, "trace") minerals*

193-1191A-

2R-1, 32-36 1 Slightly altered, aphyric, moderately vesicular rhyodacite Opaline silica (plagioclase, marcasite, pyrite)

3R-1, 18-21 1 Slightly altered, aphyric, moderately vesicular rhyodacite Opaline silica, plagioclase (cristobalite)

3R-1, 53-54 1 Slightly altered, aphyric, moderately vesicular rhyodacite Plagioclase, cristobalite ("spinel, ?magnetite")

Core, section, interval (cm)	Unit	Description	XRD identification: major (minor, "trace") minerals*
193-1191A-
2R-1, 32-36	1	Slightly altered, aphyric, moderately vesicular rhyodacite	Opaline silica (plagioclase, marcasite, pyrite)
3R-1, 18-21	1	Slightly altered, aphyric, moderately vesicular rhyodacite	Opaline silica, plagioclase (cristobalite)
3R-1, 53-54	1	Slightly altered, aphyric, moderately vesicular rhyodacite	Plagioclase, cristobalite ("spinel, ?magnetite")

Notes: XRD = X-ray diffraction. * = the terms major, minor, and trace are applied to XRD analyses as explained in "Hydrothermal Alteration" in the "Explanatory Notes" chapter and do not imply quantitative abundances.