Thursday, October 11, 2012

Sulfur (?) at Sulphur Works

Minerals and other growths at Sulphur Works.
Once again we are at Sulphur Works, Lassen Volcanic National Park, on the side of the road near the boiling mud pot, where MOH and I spotted some very neat greenish yellow crystals, which might be sulfur (upper right, center, and lower left).

A somewhat closer view of crystals in the upper right of the first photo.
The crystals seem a little long and pointed to me for sulfur, and copiapite, a sulfate known to occur in the area, usually occurs in scaly masses or crusts, so copiapite seems unlikely.

Greenish yellow crystals from the lower left of the first photo.
Because of the location right next to the boiling mud pot, I couldn't just walk over to examine the crystals. People have been known to break through thin crusts at the hydrothermal areas in the Lassen area, burning themselves, so I didn't even think about it!

Close up of pointed, needle-like crystals.
These crystals may be elongate versions of the Sulfur no. 1 shape shown at If you can't see the java applet at mindat (for some reason, I can't see it at the moment), go here to Sulfur at The Mineral & Gemstone Kingdom; it's the "Sharp Bipyramid" on the right. Or, view the applet at the source, smorf, by searching for, or using the dropdown menu to get to Sulfur. It's the second of the four crystals listed.

Photo examples of similar Sulfur crystals: 1) elongated crystals from the Jemez Mountains, NM, and 2) needle-like crystals at, also shown here.

So, is it Sulfur or something else?

UPDATE 14Oct2012: In the comments, Ron Schott added a similar picture of Sulfur crystals from a fumarole at Nisyros Volcano, Greece, if anything, even more needle-like than these.

Related Posts:
Mud Pot at Sulphur Works
Fumarole at Sulphur Works
Views of Lassen


Ron Schott said...

I'm no expert on the subject, but FWIW I think you've got genuine sulfur crystals there. Compare to this Flickr photo from Greece:

Silver Fox said...

Thanks, Ron! That's a great picture of nearly identical crystals from a similar environment.