mystery precipitant

[roguerabbit]

First - I set up the tin chloride test. I've been doing this test now for some time, and it does work.
I grabbed a sample of dirt at my favorite claim, put it in Aqua Regia. Leaching process seemed to be working correctly - turned yellow, and made the solution a yellow to deep red. Tested with SCl - positive. I have dropped gold from AR with both SMB and Tin. Even looked up the chemical reaction with Tin - it works. Precipitate looked yellowish. Then, I tested the precipitate with the Stannous Chloride test - the test turned positive - significantly so. I cooked off all the water. Next, I took my gold to an assayer, and his instrument said there is no gold there. Anybody got any ideas? What would act like this in a solution? This precipitate slowly dissolves in HCl, but not Nitric. In addition, the ppt is not melted and in granular form - may have something to do with it.

 

[butcher]

my guess is Iron, it will make yellow , green or brown solutions,iron can resemble gold in and out of solution, iron in ore is very common and most leaches prefer iron over gold.

As far as the positive test with stannous chloride, was it violet or a false brown color?