Mastodawn

#ThinSectionThursday I've been thinking about lovely Lewisian rocks from the island of Iona today.

So here's a very weird Iona rock I collected a few years ago: marble with a large diopside crystal, showing intense stripy strain/shock lamellae in crossed polar light. something dramatic has happened to this rock (and to others nearby), but we don't know what, or when. So many mysteries....

Field of view 2mm wide. More info in Alt txt.

#Geology #Lewisian #Iona

Mineralogical Society of America 3d ago

Thin Section Thursday! Photo and caption by Peyton Ellen Kaufman, UG student at James Madison Univ.: Plane light photo. glaucophane schist, Blueschist Facies. It is likely the rock formed in a subduction zone (likely ocean-continent subduction). #thinsectionthursday #glaucophane

Mineralogical Society of America May 28

Thin Section Thursday! Photo and caption by Chloe Morgan, UG student at James Madison Univ.: PPL picture of a chondrite meteorite showing a chondrule, a round silicate inclusion. The chondrule exhibits a barred texture due to rapid cooling. #thinsectionthursday #chondrule

Mineralogical Society of America May 21

Thin Section Thursday! contributed by Reagan Elizabeth Davis, UG student at James Madison University. The rock pictured is a Kyanite Quartzite gathered near Ogilby California. (XPL) Kyanite shows low to moderate interference colors, and bladed form. #ThinSectionThursday #kyanite

Mineralogical Society of America May 15

Image and caption from Luke Meaney, James Madison University in Harrisonburg, VA. Hornblende andesite from Mt. Shasta, CA. A near perfect Hornblende in Cross-polarized light. See the third order pinks, blues, greens, and yellows so vibrant, Picasso would approve. #thinsectionthursday #hornblende

John Faithfull 🌍🇪🇺🏴󠁧󠁢󠁳󠁣󠁴󠁿🧡✊🏻✊🏿Apr 26

Thanks to @History_of_Geology I know today is the birthday of Leopold von Buch, after whom the glassy rock "buchite" is named. 🎂

Mull is particularly famous for its aluminium-rich buchites, in which mullite was discovere + sapphires and other goodies. Here's a mullite buchite from an old #ThinSectionThursday - the long crystals are mullite, the clear background is glass, + together they are buchite. 🤩 More in alt txt.

FoV ca 1mm wide. #Geology #Microscopy #Mineralogy #IsleOfMull

John Faithfull 🌍🇪🇺🏴󠁧󠁢󠁳󠁣󠁴󠁿🧡✊🏻✊🏿Apr 23

#ThinSectionThursday A garnet monster about to gobble up a shoal of elongate sillimanite crystals.

Garnet-sillimanite quartzite from Western Australia. Field of view 2.5mm wide.

#Geology #Microscopy #Metamorphic

John Faithfull 🌍🇪🇺🏴󠁧󠁢󠁳󠁣󠁴󠁿🧡✊🏻✊🏿Apr 17

It may be Friday, but it's never too late for #ThinSectionThursday 😁 🤡 Here's a rock (from @geologymull) newly photo'd yesterday: a lovely fresh olivine dolerite from the very-rarely-visited Stac Mhic Mhurchaidh, an uninhabited rock west of Iona. The violet colour of the clinopyroxene crystals "bespeaks titanium" as the early C20th geological survey reports elegantly used to say. 🤓 😊 Field of view about 3.5mm wide. More image info in Alt-txt.

#Geology #Mineralogy #Mull #Igneous #Microscopy

Mineralogical Society of America Apr 16

Thin Section Thursday! Plagioclase and pyroxene in basalt (Cross polarized light). Pyroxenes are mostly brightly colored, plagioclases are gray. Contributed by Bernhard Seubert. You can contribute too! Send image(s) and short explanation to akoziol1 at udayton dot edu. #thinsectionthursday

Bill Minarik Apr 16

A garnet muscovite schist in cross-polarized light. Horizontal field of view ~ 4cm.

#ThinSectionThursday #Schist #Metamorphic #Pelite