Small Brownstone Pottery Jar

I found this small brownstone jar and could not find a photo of it. I can't figure out why there is a yellowish square on the bottom that I also can't figure out. It did not have writing on it, I just tried to scratch the it off as I thought it was a label, but it was not. I can't imagine liquor in that small a jar just because it would not seem worth it to sell it. It measures about 5 1/4 inches tall and a little over 4 inches in diameter at the widest area. Any ideas what it was used for, how old and brand or anything else? Thank you.

 

spirits possibly...

 

Thank you.