FMF - Friends of Minerals Forum, discussion and message board

[Peter V.]

Thank you Pvpind.
I would like to ask you some more questions but this does not seem the right place to discuss. Could you please contact me via email or send a pm?

[Riccardo Modanesi]

Hi Peter, hi to everybody!
I agree with Pvpind. The rocks Peter found are pumice, not perlite. Perlite is the mother-rock of the "Apaches Tear" oxydiane, and it is the rock Pvpind sent us in this forum. The one Peter represented here is very common in Southern Italy, particularly close to the volcano Vesuve near Naples, and it is the rock which destroyed the town Pompei in the year 79 after Christ during the eruption of the Vesuve. If you go and visit the archaeological site of Pompei, then you will even find tons of pumice, it is very very common!
There is another interesting proof: pumice swims on water and doesn't sink, differently from almost all of the other rocks and minerals! Try with your rocks, Peter!
Greetings from Italy by Riccardo.

[Peter V.]

Thanks for your suggestion Riccardo.
The water test: The larger ones (3/8 mm) all sank except for 1 that floated for about 30 secs and with the smaller ones (1mm) about 15-20 % stayed floating.
Is it possible I have perlite and pumice?
What is the difference between Perlite and pumice?

[Joseph Taggart]

Perlite is a volcanic glass that has absorbed moisture over geologic time. Until it is popped it is not light and does not float on water. The final popped product requires

" ...an expansion process due to the presence of two to six percent combined water in the crude perlite rock. When quickly heated to above 1600 F (870 C) the crude rock pops in a manner similar to popcorn as the combined water vaporizes and creates countless tiny bubbles in the softened glassy particles. It is these tiny glass-sealed bubbles which account for the amazing lightweight and other exceptional physical properties of expanded perlite.
Expanded perlite can be manufactured to weigh from 2 lbs/ft3 (32 kg/m3) to 15 lb/ft3 (240 kg/m3) making it adaptable for numerous uses, including filtration, horticultural applications, insulation, inert carriers and a multitude of filler applications."

Since your light colored pebbles are a recently erupted natural material, has visible crystals and has not been processed by man in an oven, it is not perlite. The only thing that it has in common with processed perlite is that it is light in color and some of it floats in water. What you have is pumice, a frothy natural glass. Unfortunately, judging by the crystals visible in the pictures the samples do not look like a uniform glassy pumice, and are not of a quality to be used as an abrasive.

Sorry, but about the only thing I can think of selling it for, is landscaping gravel or possibly gravel for a light weight concrete. But that, of course, brings up the problem of "who in your neighborhood wants any more?"

I hope this answers your questions, but sorry that it is not the economic solution to your problem.

Joe Taggart

[vic rzonca]

Peter V, after reading these posts, a thought. I'm not sure what the filler is in the new light weight sheet rock, but that might be an outlet for your gift from the earth. Good luck.

[Peter V.]

Thank you for your detailed reply Joseph and thank you Vic for your advise.

What if I expand the pumice and then crush it to make bricks? or make bricks of the pumice in its whole form.
Does pumice have the same insulating characteristics as perlite?
If so, could I not use the pumice as part of a mixture to make bricks/hollow blocks?

Side note, from a reliable source I have heard that our pumice is very similar to the american perlite/pumice according to a chemical analysis but the question is how good quality is the american product?...
Which characteristics determine the quality?

Can anyone recommmend an lab that provides good chemical analysis on perlite/pumice and chromite ore (magnetic blacksand)?

Once again thank you for your time everyone.

Kind regards,
Peter

[Tracy]

Perhaps you could continue this conversation by private message (PM)? As already mentioned, this is a forum for people who collect and enjoy mineral specimens. It is not a forum for commercial uses of minerals. Now that you have your answer, any further conversations about processing and quality need not be shared with our minerals community. I don't wish to sound mean, but this discussion is outside the scope of FMF.

Thanks,
Tracy

[Peter V.]

I'm sorry Tracy but I could not PM because I am still in my trial period.

[Jordi Fabre]