What Is This Thing?
Sunday April 2, 2006
I ought to know what these objects are, but I don't. My brother reported them from tuff in New Mexico. He says they're from 5 to 8 centimeters across. If you know, leave a comment here, or come to the Forum and let us know. If you haven't been to the Forum before, you'll need to sign up for an account (and I swear that About.com doesn't do anything with your personal data). The link is down the page on the left side.
Comments
it may be Zeolite or Hydroborasit.(the picture have not enough resolution.)
Pansy Shell fossil?
The zeolite called Thomsonite forms spheres like that, but usually it grows in gas cubbles in basaltic lava.
It could be formed by the contraction which suffer the volcanic rocks during their cooling. Itīs similar to spherules, rose structures, etc…
My vote is for zeolite. In Nova Scotia, Canada there is a formation called the North Mountain basalt that is essentially an amygdyloidal (sp?)basalt that is formed by chemically rich thermal fluids flowing within the cooling lava and precipitating out in the voids formed.
looks like spherulites. however a better resolution is requested
looks like a sand dollar fossil…
Probably one of the acicular zeolite minerals, most likely natrolite, which form radiating crystal “balls” in basalts and other lavas. Other minerals in the zeolite series like mesolite, gonnardite and scolercite have a similar habit but are impossible to identify w/o chemical analysis and a better photograph. Definitely not of biological fossil origin.
Sorry I forgot thompsonite, which is another zeolite that forms in basalts and other igneous rocks from hydrothermal fluids. Say, Greg, what are “gas cubbles?”
pyrite rays or sprays
There is a larger image in the Forum–the thread is “mystery objects in tuff.” But see the original-size image at http://www.fotothing.com/alden/photo/4d9593cc0c0a5fce71b9779d27517228/
I meant to type “bubbles” not “cubbles,” and there is no such mineral as scolercite! Actually, I now vote for gypsum rose.