Ash Color

[JDM]

I'm new to leatherworking. I read somewhere that a way to tell if leather has been chrome tanned is to burn some and look at the ash. If green colored, it's chrome.

I pulled a piece of thin suede out of my newly acquired scrap box and burned a sliver. It's the one with the greenish ash. I also burned another slice of leather I have that turned dark.

Is it safe to assume the green is chrome tanned and black is vegetable tanned? Is ash color a reliable test?

I want to conduct an experiment comparing the corrosive effects of chrome vs. vegetable tanned leather on carbon steel. First, I need to know what I'm dealing with.