Fine Mineral and Fossil Cleaning Guide

Mineral Specimens may be poisonous under certain conditions or when mixed with cleaners.

Never heat cinnabar or stibnite. They produce poisonous gases.

When in doubt about how to clean a mineral specimen always consult a professional.

Here is a list of rules to use when cleaning with chemicals.

* Use chemicals that are clearly labeled and store chemicals that are clearly labeled.

* Keep a large container of clear water handy to wash off any chemical spills.

* ALWAYS wear safety goggles & rubber gloves.

* Don’t work alone.

*Avoid splattering.

* Never pour water into acid, always add acid to water.

* Keep an ample supply of baking soda handy for acid spills.

* Keep an ample supply of vinegar for alkali spills.

*Rinse specimens well.

Remember some minerals are damaged by chemicals or can be dissolved by liquids. Some methods may work on one type of mineral and not another.

Now to cleaning.

I always start with dish soap and warm water. If that doesn't work then I use other chemicals.

You can use oxalic acid to clean iron stains from minerals such as quartz. Use it 1 cup oxalic granular to 1 gallon of water. It works best when warm. The hotter it is the better it works. This is also true of its fumes and vapors! Do not breath the vapors.

Hydrofluoric acid is the strongest acid there is. Do not use this unless you know what you are doing. It can cause serious injury or death.

Hydrochloric acid can be used to dissolve carbonate minerals and deposits. A 5% to 10% solution is more than enough to do the job. The fumes from this acid can cause pneumonia, care should be taken when using it. Always make sure you have adequate ventilation.

One of my favorite chemicals to clean with is Lime-a-way® or CLR®. They remove oxidation from most minerals include pyrite, arsenopyrite, & galena. You can use them straight from the bottle on a very soft cloth.

To clean oxidation off of native metals (copper or silver) the best thing to use is a copper or silver polish and a soft cloth.

I once used a bottle of nitric acid to clean a large copper specimen and could not get the last little bit of oxidation off and a good friend (who happens to be a chemist) suggested a good copper polish. It worked better than the nitric acid.

Nitric acid will clean copper well, but should be used with great care as the fumes become nitric gas and can over power a person very fast. Even small amounts can cause pneumonia.

Always do a test run in an inconspicuous place first.

Here are some specific ways to clean certain minerals.

Barite can be cleaned with a strong solution of hydrochloric acid (30%).

For pyrite or marcasite, use oxalic acid, hydrochloric acid, Lime-a-way® or CLR®.

For the following you can try any acid except hydrofluoric acid. quartz, feldspar, labradorite, hornblende, tourmaline, & tremolite or any silicate mineral.

Water soluble minerals, like the salts and sulfur, use only ethyl alcohol to clean.

Ammonia or bleach can be used to clean lichens or algae off.

Soaking any mineral in any solution can cause the luster to disappear. When soaking a specimen, do it for only a few seconds at a time until you see how fast it is coming clean. Some minerals may require a few seconds to weeks in an acid.

Disclaimer:  Information is provided as a guide only.  Please follow instructions of any cleaning product you use, as well as common sense.  Rockpick Legend Company does not accept any liability for individual results.