FMF - Friends of Minerals Forum, discussion and message board

[Jason]

I just got a bunch of spodumene crystals on quartz matrix...the spodumene crystals are al;l fairly clean but many of the quartz crystals look real good are terminated and somewhat gemmy..the problem is mosy have K-spar on them. I can scrap it off but thats a slow process...can i soak them in HCL or SIO to expedite the process in helping remove the spar? Any hints or tips are welcome..so mineral junkies..what do you suggest?

[GneissWare]

Try one of the high pressure water guns...they are about $100 for a Chinese one.

[Peter]

Watergun takes some, but if you want to clean mineral seriously get an aerobrasive set, a box, and a suite of aerobrasive powders from soft plastic beads to harder....

[Jesse Fisher]

A lot of the late-stage overgrowth on pegmatite minerals from Pakistan and Afghanistan (and elsewhere) is either a fine-grained fledspar or sericite (a fine grained muscovite). Virtually the only way to efficiently remove the stuff is with an air abrasive unit and glass bead. Sericite, being a mica, is highly flexible and may take a long time to remove even with this technique. From my experience, a water gun often has only limited effectiveness unless the coating is fairly loose to begin with.

[GneissWare]

I only suggested a water gun as it is about 18 times cheaper than am air-abraide unit. On some of the Pakistan quartz the coating will respond well enough. It will not remove it all however, but it may remove enough.

[Jason]

Never really did much research on air blasters/glass beads..can someone elaborate a little on this..probably just google it..I wonder if i can find one on ebay or something not just for these but for future instances also..thanks anyways guys..i will look into both the water gun and air blaster...

[Jason]

Found this on mindat..and they had a spodumene and quartz crystal specimen with the same type coating used as an example..so might try this(don't feel like copying the pics)
"7. Cleaning Quartz with commercially prepared reagents containing small amounts of bifluoride.
Here is a quartz cleaning technique that was suggested and documented by Mindat member Nik Nikiforou that appears to be so practical and good we are presenting it here for all Mindat members. If you are familiar with the way specimens look, especially quartz crystals look when they are freshly collected from a pegmatite pocket you will want to at least know this method of cleaning them, especially if you don't have any air abrasive tools at your disposal. Even if you do, you may want to give this method a try. Look at this before and after image of this Quartz and Spodumene var. kunzite specimen. Although the before picture is not very sharp and not taken of the specimen in exactly the same position as the after shot, it is plain to see that the cleaning of the specimen was very effective.


Kunzite & Quartz, Konar (Kunar; Konarh; Konarha; Nuristan) Province, Afghanistan----BEFORE
Kunzite & Quartz, Konar (Kunar; Konarh; Konarha; Nuristan) Province, Afghanistan----AFTER


Although you can probably prepare a similar reagent using ammonium hydrogen fluorite (ammonium bifluoride a white poisonous powder)we would recommend you use a commercially prepared reagent called Whink. This is one that should easily be obtainable here in the United States. There are probably others. Perhaps someone will come forward with a formula and reagent preparation procedure for a similar reagent, but till then, this one will do well. For those of you in foreign countries who may not have access to this particular brand of bifluoride reagent I would advise you to ask or pay an industrial chemist to whip up a formula for one that you can use and perhaps even sell to others that may want to clean their quartz specimens. But for now, lets listen to what Nik Nikiforou says.

I've had good results removing the silicate "white stuff" from Quartz and other minerals using an easily obtained product called Whink Rust Stain Remover. It is a liquid and comes in a brown plastic bottle in 6,10,16 & 16 oz sizes and can be bought in many hardware stores and or on line. Before I go any further you need to know that this product contains 2% to 3% hydrofluoric acid, one of, if not THE most corrosive acids known, and extreme safety precautions need to be taken, including working with it ONLY OUTDOORS, wearing SAFETY GOGGLES and chemical resistant GLOVES. You must NOT let the liquid touch your skin and you must not breath the fumes. I can't stress that enough.

Having said that, I use it by putting the specimen to be cleaned in a LOOSELY covered plastic container (not glass as it will eat through glass!), pouring enough of the liquid in to cover the specimen, and keeping it out in the sun for several days or longer. If I need to process a large piece I will dilute it with enough water to cover the specimen, although this will prolong the amount of time needed for it to work. I will check it every couple of days by gently scraping at the white stuff to see if it has begun to soften. At that point I will remove it from the Whink and soak it in water for a few days, changing the water daily, in order to remove any remaining HF, especially if the piece is at all porous. I then gently scrape off as much of the stuff as I can with a dental tool or knife, and if the piece can physically stand up to it, hit it with the water gun. I often have to REPEAT this process two or three times (Whink treatment, water soak, mechanical removal) to get the last of the white stuff off. A lot of work, so it only pays to do this with better pieces.

[Peter]

I would NOT recommend anyone not very familiar with safety procedures working with hydrofluoric acid even to CONSIDER doing this. I have seen people put out a couple of liters in a ice cream plastic box in their back yard.... what if a child or an animal gets to it....

If you have a deserted house w a high situated balcony and NO HUMAN neighbours, you could CONSIDER it, but you would still have a risk to contaminate a bird, a squirl...

Even when using fume hoods, gloves are not enough. A tiny hole could get some HF acid seep in and make irreparable damage to you, your body.... it does not stop at the skin, surface. Better soak your hands completely in water/neutralizer every few seconds every few seconds and be ware of any minute droplet that may have squirted somewhere.....

[Vinoterapia]

Peter is quite right about the hydrofluoric acid, for those of you not familiar with it or the consequences of its misuse just think on the "Alien" movie. Remember how the alien´s "blood" kept dissolving the metal of the spaceship?, I guess the movie director was thinking on hydrofluoric acid.

Best regards.

José Luis.

[Jordi Fabre]

[arturo shaw]

I think it could be this one:
https://www.mindat.org/article.php/403/Cleaning+Quartz

Regards

Arturo Shaw

[parfaitelumiere]

the only quick way would be sanding,but it can create damages in the Kunzite,because it can cleave.
The sand hardness must be under the less hard minerals on your specimen.
the problem with glass beads is that it will create a mat instead of keeping the glossy surface of your specimen.
even on tourmaline the faces can loose their glossy surface.

[Peter]

Better use PLASTIC BEADS as much as possible!

[Jesse Fisher]

The issue of hydrofluoric acid (HF) always seems to come up in discussions about cleaning silicate minerals. I can not overstate just how dangerous this stuff is. Any skin contact or inhalation of fumes can quickly cause extensive tissue damage. Serious exposures can easily be fatal. The insidious thing about HF is that it is a weak acid and causes very little of the burning sensation associated with exposure to stronger acids, so one is not aware of the exposure until after the damage is done. If you do not have training in laboratory safety and access to professional laboratory equipment, do not consider using this stuff.

Air abrasive units can be expensive, but are well worth the investment if you are planning on cleaning any volume of material. One of the largest manufacturers here in the US is Crystal Mark. They exhibit at Tucson and have a good website. These are "professional" units and the price starts at a couple thousand USD. I have seen cheaper units designed for hobbyists available through Krantz at some European shows including Ste. Marie and Munich.

A lot of professional mineral dealers now own air abrasive units (at least here in the US), so if you are only in need of the occasional cleaned specimen, perhaps best to find someone who owns one and pay a bit for their services.

[arturo shaw]

Hi Peter, ¿Where are you Sweden or Luxembourg? I can not believe that it could be two members of the forum in a so little country, amazing!!

I'm a walking distance from "La Coque".

Regards

Arturo