Please look at the following below links which may help you in your analysis:

https://www.sciencedirect.com/topics/chemistry/apatite

Thanks

Dear Mr. Carneval,

never use HCl because apatite s.s.s. are disolved by this process as it is the case with calcite. The only way is to go through heavy mineral separation because both minerals belong to different density groups (light and heavy minerals). You can use Na polywolframate (non-toxic) and dilute the heavy liquid to a density which allows for the separation of calcite and apatite or you use directly bromoform or tetrabrom-ethane, both of which are very cheap and have a fixed density. In case of using the latter ones you should use safety gloves and a ventilation hood. The separation results are very good. I made use of them several times also for apatite separationand it worked perfectly well. You can use one of my papers saved on the RG server dealing with heavy minerals and read the methodology section.

With kind regards and much success

H.G.Dill

Thanks a lot professor Harald G. Dill

Our lab separates conodont microfossils, which are composed of apatite, from limestone, using 10% solution of formic acid with good results. The limestone is broken into centimeter-size pieces and kept in the acid no more than two days, unless the solution is buffered. I hope this works for you.

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I agree with Phil Heckel. Weak formic acid, cold, for 48 hours should do the trick, but will not dissolve dolomite or any silicate components.

Diluted acetic acid (solution about 10%) also gives very good results. Even more gentle is the dissolving calcite in the Na acetate buffer. In this buffer, for example, it is possible to successfully etch natrolite from calcite. It is also used in the separation of clay minerals from carbonate rocks for diffraction studies.