geyserite

It is located in the Upper Geyser Basin, and is situated on a mound of geyserite built by its own water.

Shepp's Photographs of the World Daniel B. Shepp

But there is no mound, and the rocks of the fissure are just beginning to get a coating of the silicious geyserite deposited from the water, so that it cannot long have been spouting.

The San Francisco calamity by earthquake and fire Charles Morris 1877

They come nearer in character to the Yellowstone geysers, their waters depositing true geyserite, or silicious concretions.

The San Francisco calamity by earthquake and fire Charles Morris 1877

For while on one side some seemed just as if they were starting into existence, on another were those apparently in the very zenith of their strength, while others again looked as if they were making but their last feeble efforts at existence, though it was evident, from the heaps of consolidated geyserite surrounding them, that they had but recently passed through halcyon days of youthful energy and manhood power.

A Girl's Ride in Iceland George Harley 1862

The geyserite, or the solid incrustations, is over 80° of silica, with

A Girl's Ride in Iceland George Harley 1862

The rapidity with which the deposits form and solidify may be conjectured when I say that I saw trees growing close to some of the geysers whose stems and lower branches were so encrusted with geyserite as to give the idea that they were actually petrified.

A Girl's Ride in Iceland George Harley 1862

Moreover, the resounding echoes from the clatter of our horses 'feet as they briskly trotted over some of the geyserite, as well as the heat we experienced through the thick leather soles of our boots as we walked across it, was unmistakable proof that but a thin layer of crust separated the surface of the globe we were traversing in Wyoming and Montana not alone from vast caverns, but likewise from still active subterranean fires.

A Girl's Ride in Iceland George Harley 1862