Thanks to @History_of_Geology I know today is the birthday of Leopold von Buch, after whom the glassy rock "buchite" is named. ๐
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. ๐คฉ More in alt txt.
FoV ca 1mm wide. #Geology #Microscopy #Mineralogy #IsleOfMull
#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.
It may be Friday, but it's never too late for #ThinSectionThursday ๐ ๐คก 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. ๐ค ๐ Field of view about 3.5mm wide. More image info in Alt-txt.
A garnet muscovite schist in cross-polarized light. Horizontal field of view ~ 4cm.
Biotite replacing garnet, from the Willoughby area of the Vermont Appalachians.
#ThinSectionThursday ๐ฅ Hot off the microscope this morning! ๐ค This may look dull, but the big clear (grey) grain with faint WSW-ENE parallel lines, on the right hand side of the image is a shocked quartz (produced by a meteorite impact).
The smaller greenish (orange) grain to the left is epidote. All the fragmental grains here been cemented together by turbid brown albite. From the enigmatic Stac Fada unit, (Proterozoic), in NW Scotland.
Mineralogical Society of America
John Faithfull ๐๐ช๐บ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ๐งกโ๐ปโ๐ฟ
Bill Minarik