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Rescuing massive 13 lb tremolite/actinolite
  
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Charly H




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PostPosted: Apr 12, 2021 12:52    Post subject: Rescuing massive 13 lb tremolite/actinolite  

Hi I am pretty new to all this, came upon this enormous piece of what I think is tremolite/actinolite (but open to other suggestions) at an auction, I do not have a location for it. Is there any way to remove that corrosion and tarnish from the outer weather rind? Is that even a thing eight this mineral? Or has this one been damaged/altered beyond saving? I have some experience using iron out and other mild acids but nothing major. Thank you for your help!


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 Mineral: Tremolite/actinolite
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alfredo
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PostPosted: Apr 12, 2021 16:50    Post subject: Re: Rescuing massive 13 lb tremolite/actinolite  

Seems likely that the yellowish brown crust is iron oxides, so a bath in either Iron Out or hydrochloric acid (neither of which will hurt tremolite-actinolite) should help, followed by some scrubbing to remove clays. If using hydrochloric acid, the piece will need a second bath in citric or phosphoric acids to prevent unsightly stains.
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Charly H




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PostPosted: Apr 13, 2021 10:31    Post subject: Re: Rescuing massive 13 lb tremolite/actinolite  

Thank you for your help, I will give it a go. I tried scrubbing but it just started to damage the specimen because the outer weather rind is very soft and brittle. I’m a little concerned about toxicity, too. What would cause this to become so corroded? Is it natural or from poor storage like pyrite rot? Thank you again.
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alfredo
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PostPosted: Apr 13, 2021 11:03    Post subject: Re: Rescuing massive 13 lb tremolite/actinolite  

Some iron minerals must have decomposed and oxidized at some point, but hard to say what they were; lots of possibilities: sulphides probably the most likely (pyrite, pyrrhotite, etc), carbonates (siderite, iron-rich dolomite, etc), even other silicates (biotite...). Unlikely to be anything toxic left in the rock, just in the chemicals you use for cleaning it; so use rubber gloves, and rinse well.
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Pete Modreski
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PostPosted: Apr 14, 2021 10:12    Post subject: Re: Rescuing massive 13 lb tremolite/actinolite  

Charly, some rocks are just dirty and weathered enough, and have enough insoluble mineral crusts on them, that they are either just impossible to clean, or would require such repeated and "exotic" chemical soaking and cleaning treatments, that it is not worth the trouble. You tremolite-etc. rock specimen likely falls into this category (sorry to say). Unless it is really, really special to you!

If the specimen were something with crystals (like quartz) that had smooth, clean, hard crystal faces (underneath all the surface weathering deposits), it might be more amenable to eventual cleaning to a "pristine" state. But tremolite, with its fibrous/platy nature and strong cleavage, having so many cracks/fractures in which "dirt" and weathered deposits (plus perhaps algae/moss, etc.) can penetrate, well, there's probably less hope.
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Matt_Zukowski
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PostPosted: Apr 14, 2021 23:06    Post subject: Re: Rescuing massive 13 lb tremolite/actinolite  

Maybe you wouldn't want to do this but if this was my rock i'd hit it with a hammer and see what was inside. Maybe you'll find something nicer you'd want to keep. If not, it will probably be because it is just too weathered, and not worth dealing with. Just my opinion.
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Charly H




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PostPosted: Apr 15, 2021 06:14    Post subject: Re: Rescuing massive 13 lb tremolite/actinolite  

I figured as much but it was worth asking, thanks for the advice! I am now tempted to crack the sucker open, what is the best way to do that? Dead blow hammer and a chisel? Would I have to worry about toxic particulate in that endeavor? My fear is that it will kind of just chip apart in minuscule pieces. It’s very brittle!
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James Catmur
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PostPosted: Apr 16, 2021 10:45    Post subject: Re: Rescuing massive 13 lb tremolite/actinolite  

Do you have a press or jack you can use to slowly squeeze a wedge into it?
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Charly H




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PostPosted: Apr 16, 2021 11:23    Post subject: Re: Rescuing massive 13 lb tremolite/actinolite  

I got a hydraulic press and a chisel! What could go wrong?!
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Matt_Zukowski
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PostPosted: Apr 16, 2021 11:55    Post subject: Re: Rescuing massive 13 lb tremolite/actinolite  

Yes indeed.
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James Catmur
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PostPosted: Apr 16, 2021 13:31    Post subject: Re: Rescuing massive 13 lb tremolite/actinolite  

Just do it slowly so it slits gently. See what you then find

Charly H wrote:
I got a hydraulic press and a chisel! What could go wrong?!
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