...Satoshi Nakano; Shoji Kojima; Kuniaki Makino; Masahiro Kayama; Hirotsugu Nishido; Junji Akai Abstract Cryptoperthitic alkali feldspars in the Cerro Colorado monzonites from the Atacama Desert, northern Chile, exhibit bluish iridescence. Three types of cryptoperthites are developed over a grain...

...M.R. Snow; A. Pring Abstract The iridescence colors of abalone shell arise from Bragg diffraction of light from the layers of the nacre. The thickness of the aragonite nacre tiles is locally regular but varies during the growth cycles of the shell and this can give rise to complex color play...

... of a broken pearl showing the aragonite crystal tiles. The aragonite c axis of the tiles projects vertically from the nacre, but the orientation of the a and b axes is not constrained ( Chateigner et al. 2000 ). The iridescent colors of South Sea Pearls and their shells have been ascribed...

...P. E. Champness; K. A. Rodgers Abstract The golden iridescence observed in orthoamphiboles from the Nuuk district, southern West Greenland has been shown by analytical transmission electron microscopy to be the result of the interference of light reflected from alternate, coherent gedrite...

...Hisako Hirai; Hiromoto Nakazawa Abstract The presence of regularly stratified layers in an iridescent garnet, predicted by an optical study, is confirmed by electron microscopic observations. Analytical electron microscopy showed that the layer texture is composed of major Fe-rich lamellae...

...Mizuhiko Akizuki; Hiroto Nakai; Teruo Suzuki Abstract Iridescence in grandite garnet from Kamihogi, Yamaguchi Prefecture, Japan, results from two chemically distinct kinds of growth lamellae, which repeat alternately parallel to (110) with a periodicity of about 2 μ m. Thin sections of grandite...

..., opalescence, iridescence and scattering of light have been applied to the peculiar color phenomenon that is probably best known in labradorite, one of the first minerals to be described from this continent. The last worker in this field after much excellent work frankly acknowledged defeat in trying to reach...

...Earl Ingerson; Julian D. Barksdale Abstract Garnets from a lime-rich layer in the contact zone of a granodiorite stock near Golconda, Nevada, show brilliant iridescence both on striated crystal faces and in thin section. They have a birefringence a little more than a third of that shown...

...Manzoor A. Badar; Mizuhiko Akizuki; Safdar Hussain Abstract Detailed investigations of the optical anomalies, surface and internal lamellar textures in a crystal of iridescent andradite from Sonora, Mexico, were made by optical polarizing microscope, electron-probe micro-analyzer (EPMA) and back...

...K. A. Rodgers; P. D. Kinny; V. R. McGregor; G. R. Clark; G. S. Henderson Abstract Golden iridescent, 1-100 mm crystals of alternating lamellae of anthophyllite and gedrite constitute the bulk of orthoamphibolite pods within quartz-cordierite gneisses of the Akulleq terrane at Simiuttat, SW...

...James P. Evans; Mitchell R. Prante; Susanne U. Janecke; Alexis K. Ault; Dennis L. Newell Abstract We document new geological indicators of ancient seismicity in the form of highly reflective, iridescent, hematite-coated fault surfaces. Small faults that cut the Paleoproterozoic Farmington Canyon...

..., and plagioclase in the range An 43–53 . The Chugwater anorthosite generally contains no olivine but is composed of augite, low Ca-pyroxene, ilmenite and magnetite, and iridescent plagioclase in the range An 50–56 . The Snow Creek anorthosite is characterized by a lack of olivine and magnetite and the presence...

...Y. Miura; J. C. Rucklidge Abstract Combined data from electron microscope, electron microprobe, and ion microprobe analyzers can be used to determine the composition and thickness of lamellae in peristerite and cryptoperthite feldspars. Blue iridescent peristerite from Hybla, Ontario has a bulk...

...Anthony P. Millman; Jorge Aurelio Valvano Abstract Selective iridescent filming produces effects analogous to structure etching on polished sections of opaque minerals. In the case of bournonite (from localities in Cornwall and Ireland), the iridescent film revealed the presence of parallel twin...