Somehow, the book has tripled in size and a new "first draft" is finally done! Now, it's time to take a little break, get the book cover
designed and start cutting some gems.
Star garnets, when found, almost always
have a thick crusty layer of limonite on them. Before a gem-cutter can assess whether a crystal is worth cutting, this rind has to be removed. I showed a quick method that works great for single pieces in the last posting. If you have a larger parcel, acid might be the way to go.
Many mineral collectors use oxalic
acid to clean quartz and other crystals. I'll be showcasing how well this method worked for my garnet. But first, I have to mention-
this is dangerous stuff. Oxalic Acid is highly toxic and corrosive.
If you're at all uncomfortable using chemicals and acids- DO NOT try
this! Before using any chemical- always
read the MSDS (Material Safety Data Sheet). They're easily found on
google as are other mineral collector's write-ups about using this
method. What's needed:
Ingredients:
Distilled Water
Oxalic Acid (also known as “Wood
Bleach”)
Iron-Oxide coated Garnet Crystals
Tools:
MSDS
Crock Pot
Good Quality Plastic Container (that
fits inside the crock pot)
Measuring Cup
Gloves (Rubber or anything acid-proof)
Safety Glasses
Plastic Spatula or (preferably) Tongs
 |
| About 1.5 pounds of garnet crystals. I also included some non-star garnet crystals (lower right) that were collected near Emerald Creek. These will never cut asteriated gems and are sometimes found on ebay. |
The container of oxalic acid says to use 12 oz. to 1
gallon of water. I mixed about half that amount: 6 oz. for half a gallon of
distlled water.
Even though I bought my crock-pot for
$2 I don't want to ruin it with acid. If there is a tiny crack or chip in the enamel, the acid will eat its way through. Instead, I'm heating pure water in the pot
and then putting it in the plastic container with the acid-water mixture and the crystals.
Heat speeds up the reaction with the
acid and cuts down on the time spent in acid. I had the crock pot setting on low and checked up on it periodically.
 |
| After a couple of days, a dark, greenish-brown tint developed in the inner container. |
 |
| The acid ate away at the majority of the outer skin. Enough, so that I know how and where to trim them. Some pieces may still benefit from a second soaking. Top row consists of the non-star garnet crystals. Looks like they have a somewhat different type of acid resistant mineral coating. |
After taking the crystals out of their container with plastic tongs, I rinsed them with lukewarm tap water
and then soaked them in fresh water. Just to be safe, I added a little baking soda into
the water in order to neutralize any residual acid. I've heard that the acid in the container can be
reused. That's where heating it in the separate containers comes in
handy. I can pop the lid on, clearly mark it, and put it far out of
reach of any children and curious cats. Much better than leaving it
in an unsecured crock pot. If you have no intention of re-using the
acid- DO NOT POUR IT DOWN THE DRAIN OR ONTO YOUR YARD. First,
neutralize the acid with baking soda or lime. Also, remember- NEVER
ADD WATER TO ACID- it will splash you.
Feel free to leave comments about using this method. This is the first time I tried it and I welcome any additional tips. I've been restoring an old cabbing
machine and am working on an article on “how to detect asterism”
in rough garnet. Also, I've been doing lots of locality research and
will be showcasing some interesting findings. Lots to look forward to in the coming months!
