( Log Out / Hematite Group.The iron analogue of Corundum, Eskolaite, and Karelianite. Change ), M = mathematician, moved to Japan for a brilliant post-doc; on to visit list! February to 5. Grain boundaries occur as dark curves; white patches are fluid-inclusion-outlined chevrons and hoppers; and white polygons are subgrains. a) The clear, fluid-inclusion-free regions could be explained by a recrystallization mechanism of grain boundary migration. Change ), You are commenting using your Facebook account. Interstices are partly filled with fine sand grains. Figure 3 illustrates thin-section views at ten locations In my copy of Tröger (there is an English translation, but its also out of print), halite (NaCl) is listed as mineral number 4. Image width is 11 mm. It was originally collected in the 1970s by Jim Minette, mine manager at Boron California. To link to this object, paste this link in email, IM or document To embed this object, paste this HTML in website. The refractive index of halite is 1.544, which is very, very close to the mounting epoxy, so halite will have a low relief and will make cleavage very difficult to see (even though halite has three perfect planes at 90). a) Migration of high-angle grain boundaries as recorded by elongated subgrains, and strain-free new material, which grows at the expense of old, heavily substructured grains. Image width is 1 mm.http://www.ged.rwth-aachen.de/Ww/projects/salt/IJES/SchlederUraiIJES2005.html. Many grains are floating in halite cement. Ok, so who is looking at halite in thin section? OC = orchestral conductor, brother, lives in DC area The presence of subgrains in both the milky and clear parts is strong evidence that the structure was not developed by grain boundary migration. Specimen is from the collection of Rock Currier (1973). Directly on the crust surface is a layer of thin fibrous halite which shows elongation along the [100] axis. Gypsum (thin section) View Description. However, the presence of subgrains both in the chevrons and in the fluid-inclusion-free region implies that the structure is syndepositional and is a product of dissolution and precipitation processes. We’re back this week to a slightly unusual mineral to examine in thin section: halite. I don’t know if I’m ever going to need to come back (Finding photomicrographs of halite is not exactly easy. Images look ridiculously cool , Overview image of a thin section of sample gamma-irradiation decorated at 100 ºC from salt layer A (457.5 m), photographed in transmitted light. Ragged halite crystal on a grain of sand from Satellite Beach, FL Halite in Thin Section. Both the fibrous and traditional forms of sillimanite are common in metamorphosed sedimentary rocks. This content is PDF only. We’re back this week to a slightly unusual mineral to examine in thin section: halite. Plane polarized transmitted light images of sample gamma-irradiated at 100 ºC. You do not currently have access to this article. (Black & white image, unfortunately.) Add tags Comment Rate. Change ), You are commenting using your Google account. ( Log Out / March, Links about today’s Japan earthquake I’m using for class today, http://www.kgs.ku.edu/Publications/Bulletins/215/, http://www.ged.rwth-aachen.de/Ww/projects/salt/IJES/SchlederUraiIJES2005.html, http://www.ged.rwth-aachen.de/Ww/people/alumni/johannes/EGU/Talk.html, Accretionary Wedge #54 – Viscosity beverages, halite vs. quartz / feldspars / calcite -> halite is isotropic, all the others are anisotropic, halite vs. garnet (though why they would be in the same rock…) -> garnet has high relief vs. halite’s very low relief, halite vs. fluorite -> fluorite has a lower refractive index (1.43) than epoxy, so it will have a negative relief / Becke Line; also, fluorite is present mainly in igneous rocks where halite is unlikely to be found, halite vs. sylvite -> sylvite also has a lower refractive index (1.49) and that’s the best way to distinguish between them, halite vs. holes in the thin section -> this actually comes up as a problem, since halite may pluck out in the polishing process; glass / epoxy will tend not to have the bubbles that are frequently found in halite, but the refractive index is about the same; irradiation may really help this situation.