1-20 OF 187 RESULTS FOR

opal

Results shown limited to content with bounding coordinates.
Follow your search
Access your saved searches in your account

Would you like to receive an alert when new items match your search?
Close Modal
Sort by
Journal Article
Journal: GSA Bulletin
Published: 11 May 2021
GSA Bulletin (2022) 134 (1-2): 348–370.
...). The outstanding character of RSS3-Ia is related to the silica cemented mudstones and chert revealed in the lithology, and the above average Si/Ti ratios in cores recovered at Site U1521 ( McKay et al., 2019 ). The opal content of RSS3-Ia is inferred to be related to the diagenetic alteration of diatom-bearing...
FIGURES | View All (11)
Journal Article
Journal: AAPG Bulletin
Published: 15 February 2021
AAPG Bulletin (2021) 105 (2): 391–436.
...David K. Larue; Christian Hager; Thomas Merrifield; Gena M. Evola; David Crane; Phillip Yorgensen ABSTRACT Unconventional opal-A and opal-CT diatomaceous reservoirs in the Monterey Formation of the San Joaquin Valley in California have produced for more than 30 yr. These opal-A reservoirs...
FIGURES | View All (37)
Journal Article
Published: 28 October 2020
Journal of Sedimentary Research (2020) 90 (9): 1037–1067.
...Shahab Varkouhi; Nicholas J. Tosca; Joseph A. Cartwright ABSTRACT Silica diagenesis leads to dramatic petrophysical variations in the host sediment across the depth of an opal-A to opal-CT transition zone. Predicting the present-day diagenetic status of opal-A to opal-CT transition zones, i.e...
FIGURES | View All (22)
Journal Article
Published: 08 April 2020
The Canadian Mineralogist (2020) 58 (2): 231–246.
...Dereje Ayalew; Raphael Pik; Sally Gibson; Gezahegn Yirgu; Seid Ali; Dereje Assefa ABSTRACT Opals are widespread within Miocene volcanic sequences in the North Shoa province of Central Ethiopia. The opal occurs as cavity fillings in a 5 m thick seam of glassy rhyolitic ignimbrite that is sandwiched...
FIGURES | View All (12)
Journal Article
Published: 05 February 2020
Mineralogical Magazine (2020) 84 (2): 343–354.
... colours that cause fiery effects to be observed on their characteristic brown base. The specific morphology of poorly ordered chalcedony (crystallinity index = 0.1–1.5) with an admixture of mogánite (av. 6.6%), micro-quartz and opal-C forming a colloform texture seems to be responsible for the presence...
FIGURES | View All (11)