Sold Out

tuff - densely welded tuff - teaching hand/display specimen

$ 7.50

Back in stock soon.

There is a progression in tuffs, from unwelded volcanic ash (the source material) to welded volcanic ash (tuff) to densely welded tuff. Further welding would result in vitrophyre, a phenocryst-bearing obsidian. Densely welded tuffs are uncommon. This tuff, a member of the Resting Springs Formation, formed from a pyroclastic flow that was particularly hot in the middle. The middle was so hot it welded into a vitrophyre, essentially an obsidian with phenocrysts. On either side of the vitrophyre the tuff was hot enough to become densely welded, almost glassy, and ceramic in appearance. This is an unusual specimen. Note the color. Darker was closer to the center of the ash flow, at a higher temperature and is more vitreous.

Flattened pumice lapilli in this densely welded tuff appear as dark lens shapes called fiamme, Italian for flames. Farther from the center of the tuff bed, where welding was not as intense, the flattened pumice fiamme are much larger and retain the pumice texture.

The Resting Springs Tuff is exposed in a spectacular roadcut east of Shoshone, in Inyo County, California. It is Miocene in age.

 

 


Ships in a Regional Priority Mail box and can share that box with other purchases. Please request an invoice to avoid overpaying shipping, by clicking the "combine shipping" button in the cart.  Click > Shipping < for shipping rates. Use back button to return to this page.

Making multiple purchases? Click on the "combine shipping" button in the shopping cart. We'll send an invoice with combined shipping. A link in that invoice will bring you back to checkout, no hassle.