How to test for Chromium(III) Oxide I got some chromium(III) oxide ($\ce{Cr2O3}$) sold as pigment, called "Chrome Green". I've been having a hard time trying to react it with $\ce{HCl}$ to make $\ce{CrCl3}$. I thought it was just hard to break the $\ce{Cr-O}$ bond.

Now I'm just afraid that the pigment that I bought was actually cut with something else, like a silicate-type of pigment. How do I test for chrome(III) oxide, if I can't get it to become a salt in the first place?
The test for $\ce{Cr(III)}$ can be performed in the solid state using an oxidative melt. You will need


chromium(III) oxide (obviously)
sodium carbonate
potassium nitrate
a Bunsen or Teclu burner
a magnesia trough or a crucible
suitable pliers to hold the trough


Mix the green pigment with up to the threefold amount of sodium carbonate and potassium nitrate, place the mixture on the magnesia trough and melt it.

A yellow melt indicates the formation of sodium chromate according to 

$\ce{Cr2O3 + 3KNO3 + 2Na2CO3 -&gt; 2Na2CrO4 + 3KNO2 + 2CO2 ^}$