Vanadinite and Manganese Oxides

Any ideas how to remove gray manganese oxide coatings from a vanadinite and quartz specimen? Ultrasonic didn't touch the gray material, and water gun is out of the question. Trying Super Iron Out for some brown iron oxides also present, but I don't expect this to remove any of the manganese oxides.

Sulfurous acid is a classical solvent of Mn oxides/hydroxides. Very suffocating. A mixture of nitric and phosphoric acids is also quoted (no proportions given). Don't know how and if vanadinite could survive.

I have successfully removed todorokite from prehnite using an acidified hydrogen peroxide solution.

Rock Currier
Crystals not pistols.

Rock, The acid/peroxide route was my next choice. What is your recipe?

Well start with the commercial solution they sell for bleaching hair and put a few drops of hydrochloric acid it in. If that doesn't work, then you may have to move up to some 30% reagent and also put a few drops of acid in it, but be real careful with the 30% and stronger stuff. Wear plastic gloves and use a glass or ceramic container.

Rock Currier
Crystals not pistols.

Thanks for the info. I'm a chemist by training, so I have access to all the necessary PPE. Turns out it was a moot point, because I dropped the specimen, and it would have had no resale value as a repair.

But you should us chemicals on the broken pieces so you will know if those chemicals will work on the next specimen you want to try it on.

Rock Currier
Crystals not pistols.