Monday, November 19, 2012

It's soft as a baby's behind.

From the metasomatic zone between Vounassa and the Aliakmon.
Range of view: 6 cm.

Friday, November 02, 2012

Nice Gneiss!

Nice Gneiss!
This is part of the old Pangaean landmass dating from pre-dinosaur times. Since then, the world split apart into the modern continents which spread about the globe, and some of them collided against each other again. When the Pelagonian fragment was hit by Africa, it was run over, and went down to a great depth in the earth, say, about 25 - 30 km. But then, seeing that it is a lot less dense the surrounding material down there, it came back up again, a process called exhumation. See all those folds in the rock? These are the well-earned battle scars of a rock that has spent much of its existence getting deformed. And now here it is, nicely sliced up on a bookcase in my office.

Monday, October 15, 2012

The "Mother Lode" -- Listwaenite
In some blog below I have a close-up of listwaenite, now here's a not quite so close, close up, showing "the sample that got away" and is still waiting for me up at Vasilitsa. It's too BIG just to dig up with one hammer -- I need some students!!
Folds, anyone?
Rumpling the carpet of sediments above the ancient collision zone of Africa and Europe gives rise to a marvelous mess of folds, here visible at the crest of the Pindos Mountains.
The Glorious God -- Acheloos!
The god of fresh water in ancient mythology demonstrates his power to erode spectacular gorges within Greece. Since all the host rocks are flysch and marls, lacking any capability of storing groundwater, the course of the river is marked by more waterfalls than can be counted... 

Tuesday, January 10, 2012

Obsequious Obsidian

Was missing a bit of obsidian for the little book, and Vangelis scanned me a piece. Obsidian with stripes (as this piece) shows the flow of the glassy material (like Venetian glass). The conchoidal fracture is due to the fact that there is no mineral structure, this is a "mineraloid" after all. Every archeologist in Greece has brought me little bits of black shiny artefacts hoping they are obsidian: apparently the stone age Greeks made knives and arrow points from obsidian from Milos Island (where there's a volcano), and to find an artefact of obsidian shows something about ancient trade. However, none of their little bits proved to be obsidian, most little bits of black chert of even serpentine. To see it, is to know it.
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Friday, January 06, 2012

Sulphides in coal...

What geologist would be disappointed if Santa Claus left them a stocking full of coal -- if the coal was all full of pretty pyrite?
Yes, Virginia, pyritite is not only caused by hydrothermal processes, but also grows in reducing conditions such as this coal seam. Except as a "pretty rock" I don't think it's ever been mined in its own right for anything of economic use.
This lump of coal is about... 6 cm across. The pyrite is pervasive throughout.
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Thursday, January 05, 2012

Synthetic ruby

Only posting this because its glow and brillance on scanning surprised me. The ring is probably from the 1920's, and has been mine for about 50 years. I never suspected that it had such a glowing soul. A Christmas gift from my mom, oh, so many years ago.
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Lava from Santorini

Once upon a time, there was a large island in the middle of the Aegean. Then it exploded, creating earthquakes, tsunamis, and a large hole in the middle of the sea. Civilizations were destroyed, myths born. And this, this lava!-- this is the culprit! Note all the holes from bubbles of volatile gasses that were the cause of the violent eruption.
Bad lava! Bad, bad!
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Unakite is...

Essentially, it's a term that describes an altered granite that consists mainly of epidosite matrix and large pink orthoclase. I don't think it has any strict scientific meaning. However, it s a stone for collectors that is "pretty when polished up." Said to be found in Oregon and the Appalachiens, it seems to me a common enough rock within Pelagonia over here. Found in the oldest of the old parts of the metamorphic terrain. I just don't know if anyone in Greece has bothered to pretty it up. Maybe we should.
Scale on this slab cut from Dina's cobble: each orthoclase is on the order of 2 - 3 cm.
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Saturday, December 24, 2011

Can you smell it from there?

From a hot spring near the site of "Thermopylae", where Leonidas bit the dust, or perhaps, the sulfur.
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