Mount Washington 1
Callan begins a new series on the geology of Mount Washington, New Hampshire with a look at a roadside outcrop of metamorphic rock bearing enigmatic inclusions. Tourmaline-bearing pegmatites are also spotted.
minerals
Mystery spikes
Mystery mineral from Mount Washington, New Hampshire: radiating needles of something black… I’d venture “tourmaline”… but you tell me.
Delicious dendrites
Hopefully seasoned readers of this blog will remember this nice chunk of limestone with pyrolusite (MnO2) dendrites growing on its surface. I took some close-ups with my Nikon microscope a few weeks ago. Here they are; enjoy! The width of the field of view in each photograph is about 1.1 cm: BTW, Mike likes dendrites, … Read more
Mystery rock with radiating crystals
A mystery rock is presented. Can you puzzle out what this beautiful thing is, and how it formed?
Radiating crystals of wavellite
My once and future Honors student Robin R. brought back some sweet wavellite [Al3(PO4)2(OH,F)3•5(H2O)] samples from her holiday travels*. Check out these beautiful radiating crystals! A penny will serve as your sense of scale. The wavellite is a “crust” on top of a layered rock that appears to be a quartzite. (The layering in the … Read more
Geology of the Richmond area field trip
On Saturday, after a fruitful 24 hours at the VCCS Science Peer Conference, my colleague Pete Berquist (of Thomas Nelson Community College) and I led a field trip to examine the geology of the Richmond, Virginia, area. We were joined by seven of our VCCS science-teaching colleagues and author Lisa Starr, a speaker at the … Read more
The tale of the hammerheaded copper tadpole
Okay, now just what the heck is going on in these pictures? (All of them can be enlarged by clicking through.) The photos are different views of the same crystal. It is a broken hexagonal prism of quartz, fading to amethyst at the distal end, found by Doug Dupin of northwest DC during the excavation … Read more
Another metamorphosed graded bed
Over the summer, when my blogging access was limited to my iPhone, I uploaded a photo (taken with the iPhone) of a metamorphosed graded bed on the summit of Mount Washington, New Hampshire. Here’s another one that I saw, further down on the mountain, on the Auto Road (famous for its iconic bumper sticker): Lens … Read more
Mineral phantasms?
Ice… serpentine… halite… What do they all have in common? I’ve discussed mineral “ghosts” here before — really, those are only pseudomorphs, where one mineral’s chemistry becomes unstable due to a change in conditions, and then a new mineral forms in the same space. I’ve also brought up the issue of clasts of minerals which … Read more
Blobiform
Whilst poking about Sunday on the fine exposures along West Virginia’s new route 55, my structural geology students and I noticed some joint surfaces decorated with pyrolusite dendrites. But I also found a nice slab which had one surface covered with a thicker coat of manganese oxide, and here the habit was botryoidal, like little … Read more