***Update Some questions I am considering to try to answer this question;
- When dissolving the powder in acetic acid, which ions are present?
- From what I've read, I haven't found any acetate salts that are not soluble in water. What other metal salts could be forming that aren't soluble?
- Which ions might be present in the rock that would not readily react with the acetic acid?
- What would be a good compound to replace the acetate ion in a double replacement reaction such that the resulting metal salt would precipitate out of solution?
- Are metal acetate salts prone to reaction with oxygen? Are the metal ions in the acetate salt more attracted to the oxygen or the acetate ion? (i.e. will my sample 'rust'?)
I am leaving the main question as-is, posting this update because asking questions is part of my problem solving process.
I was experimenting with the (air) dried residual powder residue left over from cutting this rockin my wet saw in an attempt to determine the composition of the metallic components of the rock I was working with. The rock appears to be a crystalline silicate rock of some variety. It has minimal to no reactivity with concentrated HCl in its raw form. The geology of the area indicates it was once shallow ocean, with lots of limestone and cryptocrystalline quartz and crustaceous fossils in the surrounding area. The compound in question was created by soaking the residual powder in 7% white vinegar (acetic acid) for several days with constant stirring. The remaining solution was separated under vacuum filtration and residual solid was again left to air dry for several days. After several days I noticed that the top layer of the filtrate had turned brown with blue splotches. The bottom layer was white with bright blue speckles mixed in. % isopropyl alcohol I scraped off the top layer and set aside for solubility tests. It was nearly insoluble in and soluble in water. When the mixture dissolved in water, it turned yellow.
My hypothesis was that the blue compound was copper acetate, the dark brown solution is iron(II) acetate and the yellow in solution is an iron/copper coordination complex. I also suspect there is aluminum in the rock as a USGS survey indicated the presence of muscovite in the region and calcium due to the abundance of fossilized sea shells and limestone. Though I may be completely wrong. I would love if anyone could shed some light on this for me or point me in a different direction for determining the trace elements in the rock.