Cleaning Phosphate Minerals
| The Waller Method Cleaning Phosphate Minerals | |
| A chemical method for cleaning delicate or acid sensitive mineral specimens of rust, stains and muds. Or, the removal of ferric hydroxide and manganese oxide from phosphate and silicate minerals. Overview This cleaning technique is not only gentle, but a most effective chemical technique of removing staining films, clays and material containing or composed of ferric (iron) hydroxide and manganese oxides from mineral specimens. It is especially useful for cleaning phosphate mineralization where any other acid or chemical treatments would damage the minerals. The oxides are broken down in this neutral pH solution which contain sequestering anions, thus avoiding the low pH of acidic solutions which can destroy many minerals. The Waller Method makes use of the fact that ferrous hydroxide (Fe+2) is not only more soluble than ferric hydroxide (Fe+3), but it is more soluble over a wider pH range. This solution not only works on films and stains, but will break down muds and clays held together by iron or manganese ions, making their removal easier, especially with an ultrasonic cleaner. In my experience, I highly recommend this method for the cleaning of pegmatite phosphate minerals. There just is no other method to use! If plain water and soap won't remove it, give this solution a try.
|
| Introduction The following describes the chemicals used for the Waller Method, how to use them and the precise recipe to use. Please be precise in all measurements as the chemical ratios of this recipe are designed to be the most effective. Do not substitute other chemicals with similar names. Using different amounts and other chemicals might result in damage to certain minerals and be a hazard to you. Using this recipe should guarantee the proper results. Although not a true acid, treat the Solution as if it was and observe all precautions when working with this Solution. |
| The Chemicals The Waller Solution involves the use of three sodium salts and it is not mandatory to use laboratory grade chemicals: • Sodium Citrate or Citric Acid - to sequestrate ferrous ions • Sodium Bicarbonate or Baking Soda - as a buffer to maintain pH neutrality • Sodium Dithionite - as a reducing agent, turns Fe+3 into Fe+2 • Water - tap water or distilled (better) |
| Mixing the Stock Solution A Stock Solution is first made by dissolving 71 grams of sodium citrate and 8.5 grams of sodium bicarbonate in 800 milliliters of plain water, but distilled water would be better. When dissolved, add water to make a 1 liter volume. Keep this Stock Solution in either a plastic or glass bottles. This Stock Solution will keep for a very long time. |
| Mixing the Stock Solution - To make 1 liter of Stock Solution • Sodium Citrate - 71 grams • Sodium Bicarbonate - 8.5 grams • Water - dissolve the above in 800 ml. of water, then add water to make 1 liter of Stock Solution. |
| Mixing the Waller Solution Note: Only add the final chemical when you are ready to treat minerals. For every 50 milliliters of Stock Solution you are going to used, add 1 gram of sodium dithionite, No more, No less! Be exact with your measurements. Once dissolved, this is the working Waller Solution and it has an active life of 12 hours (more later about solution life). Do not mix in the sodium dithionite to this stock solution until you are ready to clean your minerals. Its life is short because Sodium Dithionite is readily oxidized once in the Stock Solution. At the same time all of the chemical are destroyed in 12 hours, making it safe to dispose of normally. You can not regenerate the Working Solution by adding more chemicals. Use once and dispose of it. |
| Mixing the Working Solution • Waller Stock Solution - For every 50 ml. • Sodium Dithionite - add 1 gram Example: For 1 liter (1000 ml.) of working solution, add 20 grams of sodium dithionite. |
| Page 1 | Page 2 | Page 3 | Page 4 |
| Top | Next Topic  |
| Updated: January 1, 2009 Webmaster: Raymond Sprague For more E-Mail information & Inquiry: Maine Pegmatite Workshop URL: http://homepage.mac.com/rasprague/PegShop Copyright - ©2005-2009 Raymond Sprague - All Rights Reserved of layout, design & revisions Copyright - ©2005-2009 Maine Pegmatite Workshop- All Rights Reserved of Name & Logo's |