After several washings of shale samples in search of microfossils, each time we obtained the same results, a species of foraminifera and radiolarians, we followed the standard method, with water, hydrogen peroxide , soap, vinegar... but in the end it's the same
Hi Brahim,
Maybe this is an option to consider? Place the (sieved) residue in a sieve and try an ultrasonic bath. There no need to fill the bath to the top with water. Consider doing some tests the exposure time (e.g. from a few seconds to maybe a few minutes) as fragile material may break by ultrasonic cleaning.
Dear Brahim
You mentioned that your already tried 'soap'. If you mean a tenside like Rewoquat, then the only other good option for removing the white stuff in the cavities (besides Frank's suggestion) could be the concentrated acetic acid method (= not vinegar) proposed by Lirer (2000). I assume that this white stuff is not just shale, but too a large extent secondary calcite, in which case Rewoquat will not help. Preservation wise, your Cretaceous assemblage looks quite familiar and in fact fairly clean, but it suffers from recrystallisation and probably calcite infilling.
Please provide feedback later on the effectiveness of the suggestion made by Frank Peeters!
Thank you for your anwsers, I tried ultrasonec procedure for 2, 5, 15 and 30 munits , the result no change.