Discussions

💬 Home 🔎 Search 📅 Latest

╳Discussions

💬 Home 🔎 Search 📅 Latest

Groups

Recent Images in Discussions

GeneralSulfur blobs: Why not crystallized?

30th Mar 2015 05:06 UTCKyle Beucke 🌟

Greetings,

I have some altered, silicified rock from a California gold mine (high sulfidation epithermal type) that has blobs (and some crystals as well) of sulfur in vugs. This deposit type involved gases and fluids rising from magma, so the presence of sulfur isn't unusual, and sulfur is common in the shallow portions of these gold deposits. But what does the morphology suggest (if anything) about how this sulfur formed? Is this a fairly common morphology for sulfur in shallow environments?

Thank you,

Kyle

30th Mar 2015 06:41 UTCAlfredo Petrov Manager

I can't answer your question, Kyle, but I've seen identically melted-looking spherules of native sulfur partially filling vugs in hydrothermally altered andesites at a little place called Katase-Shirata in Japan. I have assumed that the sulfur was originally crystallized and melted later because of some transient increase in temperature, but that's just a wild guess and it may be that this is a hydrothermal growth or dissolution feature and nothing to do with actual melting at all?

30th Mar 2015 06:56 UTCKyle Beucke 🌟

Alfredo,

Thanks, that is an interesting idea I had not considered! (That the sulfur may have been crystallized first, then melted)

Kyle

30th Mar 2015 07:18 UTCJason Bennett

Hi Kyle,

I've seen similar textures when I was trying to create synthetic bornite for experimental purposes. Basically I was mixing sulfur, copper and iron in the right stoichiometric proportions, and cooking then in an evacuated silica tube at ~600-800degC to react, hoping that they would equilibrate into bornite. They didn't the first time, because the sulfur speciated into a vapour phase (which I subsequently corrected for by adding excess sulfur, which worked). The point is, when I pulled these experiments out I was able to watch them quench: The red sulfur vapour condensed into a red sulfur liquid, which had that shape as above due to surface tension. They then eventually set into yellow native sulfur.

These blobs look exactly like that, it could be collections/droplets of native sulfur liquid from a fluid phase (either a vapour or another immiscible liquid) which then cooled into the solid state.

So it could also be a 'primary' texture, rather then re-melting of existing crystals.

Just a thought,

Jason

30th Mar 2015 11:24 UTCAlfredo Petrov Manager

Kyle, I like Jason's explanation: a drop of liquid red sulphur that cooled.

On a side note, there are places in Japan where pools of liquid native sulphur exist permanently, in contact with water that is hotter than the melting point of the sulphur. (So don't believe those folk who claim that native mercury is the only liquid mineral ;-) )

Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 25, 2024 01:03:23

Go to top of page