Dear colleagues,
I`m trying to find out what is the best method to wash the clay to look after microvertebrates. The rock is a clay with rare intercalations of sand/silt .
Thank you in advance!s
Bogdan H.
And this article might come in handy: https://www.researchgate.net/publication/230191721_Collecting_isolated_microvertebrate_fossils
Article Collecting isolated microvertebrate fossils
Thank you very much, Oleksandr, but the H2O2 won`t destroy the tiny bones ? And what is the concentration of the solution? Could you be more specific about the method ?
Dear Bogdan! Please find the file enclosed which can be useful for you.
You can also find additional information concerning your question at this forum: http://www.thefossilforum.com/index.php?/topic/35482-using-peroxide/
Dear Bogdan,
Try first to soak the sediment in distilled water for a day. If samples are partially indurated treat with warm H2O2 to improve disaggregation.
Best,
Simona
And this article might come in handy: https://www.researchgate.net/publication/230191721_Collecting_isolated_microvertebrate_fossils
Article Collecting isolated microvertebrate fossils
Dear Bogdan,
You should always be aware of type of preservation of the bones before chemical treatment. If the bones are permineralized with silica or carbonate most methods apply. On the other hand you must be careful if the bones are pyritized, replaced with malachite, chalcopyrite etc... chemical treatment my cause oxidation and increase in voulme and your material will shatter. Also be extremely careful when dealing with subfossill bones.
My methods of "cleaning" macrovertebrates are following:
- 10% or less hydrogen peroxide (H2O2) solution. I put about 120 mL 10% H2O2 solution into 5 L of water. You should always start with lower concentrations, and see what works the best for you and give it time!
- Soap, simply put soap (dish washing, shampoo, ...) into the warm water, it should affect polarity of clar particles and they will fall off.
- For etching purposes - to enhance contrasts of predatory traces I use very weak citric acid. But I DO NOT recommend doing that on microvertebrate remains!
Best regards,
Aleš
I think initially use 6% H2 O2 and apart from above you can also add some dispersing age like Sodium hexametaphosphate for processing clay.
Dear Bogdan.
At first, thank you for invitation to this discussion. Our method is much simple than already proposed. We put clay into a bowl, and then add a lot of clear water, mix gently and pour the suspension, and repeat this operation few times. Concentrated coarser residuum we strain on a sieve (usually 0,25 or 0,125 mm) keeping it in water (as gold prospectors). Of course, we add some dispersive agents sometimes (as mentioned in previous answers). Finally, we separate fossils under a stereomicroscope. If the bones are covered by carbonates, we sometimes remove the incrustation with 15% acetic acid (however, this operation, as well as treating with other media, exclude the bones from geochemical analyses).
In general, there is no the best method. Each case must be tested individually because of various clay composition (both mineral and chemical) and state of bones preservation (e.g. minerals filling internal spaces). Each method can lead to fragmentation of small bones and, in the case of clay sediments, there is no way to avoid it, because almost all bones are cracked and they easily break up into smaller fragments under any action. Thus, you have to find your own method, which will the best for your material and for purposes of the study.
Regards,
Adam Bodzioch.
dear Bogdan,
I was about to recommend to you the Ward-paper 1984, when I saw somebody already recomended it.
good luck, Francien
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