FMF - Friends of Minerals Forum, discussion and message board

[Shan]

Plz help me!! and i need some suggestion that how i can remove that hard port from my tourmaline crystals.

[alfredo]

I'm assuming the crust is either a mica, chlorite or feldspar mineral.

1) Try high-pressure water gun first (they are manufactured very cheaply in China).

2) If that doesn't work, try air abrasive blasting with glass beads - That will almost certainly work well, although the tool is expensive.

3) Cheapest method is dilute hydrofluoric acid, but dangerous unless you have experience with using nasty chemicals. A short bath in dilute HF will dissolve the weaker silicates without noticeable effect on tourmaline.

[Shan]

whats the method? do i need to put that HF acid in water and then throw the crystals in them?

[alfredo]

Shan, you obviously don't have experience with HF, so it would be too dangerous. Find someone who has used HF before and ask them to do it. I don't want to be responsible for you going blind, or worse.

[Shan]

Ty so much! Alfredo i wil find someone to do for me :)

[GneissWare]

[ellencmoe]

I find Oxalic Acid works pretty well on clay deposits on tourmaline and is a little safer to use than HF or HCL acids. In the US, oxalic acid is pretty easy to buy. I mix a solution of the oxalic acid crystals in warm distilled water in a plastic or glass container- wearing gloves and being careful not to breathe the fumes. Then I soak the crystals in the covered container outside. I check the crystal frequently and soak in clean water for at least as long as they soaked in the acid once they are clean.
Alternately soaking and scrubbing and then letting the crystals dry sometimes helps get the clay deposits off.
In the US, you can also buy a kitchen cleanser called Barkeepers Friend. This has oxalic acid and I use it on with crystals with an old toothbrush. Always wear gloves with this also, oxalic acid can be absorbed through the skin and in some people can contribute to kidney stone formation.
If the white deposits are feldspar, not clay, soaking in acid usually does not help. I have some old dental tools from my dentist that I use to gently and carefully try to scratch this off.

[Joseph DOliveira]

[Jordi Fabre]

And you can also write the word "hydrofluoric" in the Forum's search: and you will find some previous messages where we discussed about the cleaning of Tourmalines as well as the right use of the very dangerous hydrofluoric acid.