Please don't touch goethite

[MORGAN]

Yeah, I should have known that Goethe doesn't have an R in it...leave it to the guy with an umlaut in his screen name to set me straight on German pronunciation!

[Kelly Jessop]

What I am talking about is flat rocks that randomly appear in Peacock,or are in piles on a debris mound. They are black,and have ripples,almost like the tread of a car tire.

[RN]

Can you post s picture of such material.

Sent from my Eris

Adam, you know the brown colored formations that come off the ceiling in downstream Hole in the Wall from about 300' to 600'? That's goethite.

[skip]

so why does touching such a rock matter? i saw you say it turns brown (or white), but does that mean the black is the mineral and the substance under (white/brown) is the substrate upon which the blackness is attached? what's so special about this black stuff that makes it not ok to mess with, while "ordinary" limestone is ok to mess with? I pick up a white/brown rock and place it on the line, or I pick up a rock covered in black. what's the diff? not trying to be unconservative, just not so sure go-eth or gurtay or whatever is anything special. sounds like it's as common as limestone and dolomite and just another rock like any old rock.

skip

[Jim Wyatt]

Can you post s picture of such material.

Sent from my Eris

C'mon Marine!! You don't know what geothite is?? If not..drop and give me 20.

[skip]

Adam, you know the brown colored formations that come off the ceiling in downstream Hole in the Wall from about 300' to 600'? That's goethite.

brown? I thought it was black. Now I'm really confused.

skip

[adam0321]

Got it thanks.

Sent from my Eris

[Rich]

I can't help but think a better title for this thread would be please don't touch the cave......
There are some instances where it's sometimes okay eg on flow-hardened limestone, but you really shouldn't ever be touching stuff in a no or low flow cave, should be a matter of pride, ya know!
BTW if anyone wants to see a superb example of diving in a high flow cave without touching anything, pick up a copy of the "Bat Circuit" DVD by the late Harvey Boyd where the diver being filmed is funnily enough, Kelly Jessop.....

Safe diving,

Rich

[SuPrBuGmAn]

so why does touching such a rock matter? i saw you say it turns brown (or white), but does that mean the black is the mineral and the substance under (white/brown) is the substrate upon which the blackness is attached? what's so special about this black stuff that makes it not ok to mess with, while "ordinary" limestone is ok to mess with? I pick up a white/brown rock and place it on the line, or I pick up a rock covered in black. what's the diff? not trying to be unconservative, just not so sure go-eth or gurtay or whatever is anything special. sounds like it's as common as limestone and dolomite and just another rock like any old rock.

skip

The same reason its not OK to pull and glide on a clay floor, leave hand prints in the silt, and generally any other obnoxious activity in a cave that makes an obvious/easily avoidable contact mark in a cave.



Remember that old saying... leave nothing but bubbles, take nothing but photographs, or something like that?

[Squirrel Girl]

so why does touching such a rock matter? i saw you say it turns brown (or white), but does that mean the black is the mineral and the substance under (white/brown) is the substrate upon which the blackness is attached? what's so special about this black stuff that makes it not ok to mess with, while "ordinary" limestone is ok to mess with? I pick up a white/brown rock and place it on the line, or I pick up a rock covered in black. what's the diff? not trying to be unconservative, just not so sure go-eth or gurtay or whatever is anything special. sounds like it's as common as limestone and dolomite and just another rock like any old rock.

skip

Well, there you go! That's why I get anal. It's all about texture! Well, and a little more than that, too. So you take limestone. It's medium hard. It tends to be buff colored to tan and in some places is dark grey (but not in FL). It can be scratched, but except for a few limestones, it generally takes a little effort to scratch it (not nearly so much as granite).

Goethite is a mineral that coats the exposed surface of the limestone as spring water runs across it (I can't say I am boned up on the geochemistry of it all, but if you have more questions I can attempt an answer). The color is a dark brown that ranges to what my eye would call black. One could probably do a detailed study of the colors of geothite, but I'm not sure what you would gain from it. Just consider it dark brown to black.

The formula is: α-Fe3+O(OH)

In the crystal habit that it forms in caves, it's not nearly as hard and durable as the underlying limestone. So when you touch the rock (see the picture I posted earlier), it scrapes the brown-black goethite off the the limestone. It takes a very long time to form (though I don't have any rates at my fingertips). So when it gets worn off the cave, you and I won't see it regrow before we die. Conservation-minded folks would say that it's just not right for me to deface the cave so others don't get to see the pristine cave as it used to be.

That's different than if I pick up a piece of limestone and drop it again. I haven't really changed it in any visible or appreciable way, so no one complains about that (under most circumstances).