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[Kaljaia]

I traded a thunder egg half for a chunk of Trent agate recently. Figure it's not a material one comes across frequently so might as well see what it's all about! It's neat stuff, but it did a number on my saw oil and now it's yellow and smelly and it's depositing yellow on everything else :P oops. That'd be Orpiment, I guess?
At any rate, it is pretty. The back of this chunk has bright yellow on an exposed face- is the realgar in Trent known to decay to orpiment or is it fairly stable?





I'd hazard a guess the small amounts of orpiment this distributed into my saw oil aren't going to be a long-term problem :P

[Stonemon]

Erika,
I have been cutting Trent for years and have never had a piece discolor the oil in my saw. The rock you posted is a very unusual piece that has some characteristics I have never seen in a Trent Agate.
The volume of orpiment is staggering. The absence of realgar is different and the lack of black sagenite is very unusual. The white rind is typical of the agate I have.
I have a couple hundred pounds of rough but nothing quite like that piece. Makes me wonder...... Smelly makes me think sulpher.
Did you pick it up in Prineville?

[ileney]

Amazing looking. Very atypical.

[Kaljaia]

Erika,
I have been cutting Trent for years and have never had a piece discolor the oil in my saw. The rock you posted is a very unusual piece that has some characteristics I have never seen in a Trent Agate.
The volume of orpiment is staggering. The absence of realgar is different and the lack of black sagenite is very unusual. The white rind is typical of the agate I have.
I have a couple hundred pounds of rough but nothing quite like that piece. Makes me wonder...... Smelly makes me think sulpher.
Did you pick it up in Prineville?

No, I got offered it in trade for half a thunder egg from my own claim- figure if it isn't "truly trent agate" it's no problem on my end, it'll still be plenty interesting and the price was fine with me. It came from another Oregon collector who had a crate of it he'd picked up somewhere, I think an estate sale so who knows who or when it came out of the ground. The cut piece he had from that crate was much more typical black sagenite with white agate and some red. The back side of this piece has a spray of yellow decayed realgar or orpiment, the front was lots of vugs with the spiny sagenite. I'll get it cleaned up here and post pictures of the outside. If it isn't Trent I'd sure like to know what it is! Realgar being an arsenic sulfide the smell makes sense. Very swampy, pyrite-like. But yeah, it isn't looking like Trent I've seen before at shows or online.

[catmandewe]

Nice trade!

[R.U. Sirius]

Just a thought - depending on your saw, arsenic sulfides might be exposed to enough heat in the blade contact zone to decompose into arsenic oxide and sulfur dioxide. This might explain the smell (sulfur-like, coal burning smell?).

Also a warning that arsenic oxides are much more hazardous than sulfides, and may be absorbed through skin contact. Be careful, everyone. As someone who has been working and playing with all sorts of chemicals for over 25 years now, I can tell you that the devil is in the details.

[Kaljaia]

Just a thought - depending on your saw, arsenic sulfides might be exposed to enough heat in the blade contact zone to decompose into arsenic oxide and sulfur dioxide. This might explain the smell (sulfur-like, coal burning smell?).

Also a warning that arsenic oxides are much more hazardous than sulfides, and may be absorbed through skin contact. Be careful, everyone. As someone who has been working and playing with all sorts of chemicals for over 25 years now, I can tell you that the devil is in the details.

That's a good thought. My saw in general runs cold since upgrading the coolant system to truly flood the blade. I don't remember specifically checking blade temp when I cut this but the fresh cut rock was cool to handle and the blade wasn't heat-soft like it used to get on big hard agates. I babysit the saw, so was handling rock within seconds of the cut finishing and don't remember it feeling hot. Either way I don't plan to cut more of this! I do need to clean the oil now, which is a pain. I just cleaned it a couple weeks ago but the orange dust is deposited throughout my tubing.

[Stonemon]

So after looking very closely at your pictures, I think it is a Trent. A very unusual one but a Trent none the less. The closeup of the slab appears to show quite a bit of live sulphide. I assume that this metal is arsenopyrite given the prevalence of arsenic in the rock and when I cut Trent with a lot of live sulphide, I get the sulpher smell also.
The discoloration of your oil would be a logical outcome given the huge amount of orpiment and realgar present.
Do be careful if you decide to mess with it or cab some. I always wear a respirator, gloves and eye protection when I am playing with the stuff. A while back I got screened for heavy metals in my system and all was normal except my arsenic, which, while in the normal range, was elevated near the top of the normal range, lol
Anyway, thanks for sharing your beautiful rock. I will be keeping my eyes open as I work through my stock for something similar...