The crystallization of large replenished magma bodies is amazingly complex. The photos of layered rocks from the Bushveld Complex in this new #OpenAccess paper are mind-bogglingly wonderful 🤩 🤯 🤓 . The wider applicability of their conclusions might be disputed by some, but good stuff though! https://doi.org/10.1016/j.lithos.2024.107621#Geology#Igneous#LayeredIntrusions
My two minor obsessions captured at the same moment. Here are pictures of my favourite bicycle, an old school build using a custom #DaveYates frame, resting against my favourite rock, a beautifully smooth #glacial erratic composed of a very hard, fine grained, mid grey #igneous rock with pale mm-cm sized plagioclase phenocrysts. Generations of bottoms have enhanced the glacial smoothing 🙂. Located in #MaxwellPark#Glasgow#geology#cycling
Some #DogWalkingGeology from last week. Spud is pointing out some nice layered gabbro-melatroctolite from the Ben Buie Complex in SE Mull. 😊 #Geology#Igneous
Okay, #stibnite vs #sodalite. Stibnite is cool, but I have to be #TeamSodalite in this matchup. I've always been fascinated by sodalite and all of the related #nephelinesyenite minerals that only occur in very special silica poor or absent melts. They are like the #BaltimoreOrioles kicking ass over the #Yankees (and I already championed #Quartz as the Yankees). Plus, sodalite is an awesome blue color and flourescent under UV. How cool is that!!!!???? #MinCup23
Though not perfectly developed in the Mt. Ashland Pluton, the leucocratic granite pegmatites near the summit display a weakly graphic texture.
“Graphic granite is a leucocratic granitic rock consisting of alkali feldspar with exsolved quartz typically forming a distinctive repetitive pattern sometimes resembling cuneiform writing. Experiments have shown that graphic granite texture is derived from large single crystals of quartz and feldspar interleaving to create the cuneiform illusion.”
Wikipedia
In this sample, the development of the texture has been explained as an immiscibility between the two primary crystallizing components (quartz and feldspar) and the remaining magma…while others explain it as the nucleation and growth of quartz, controlled by the host feldspar, which supports the simultaneous growth of quartz and feldspar that results in the graphic granite texture.