Hand formed stoneware

What I know:
The vase/vessel is a little under 7" tall, is approx 6" diam at the widest, and is on a base a little over 3" diameter. It is relatively heavy and has thick walls. The clay portion appears to be concrete-like but has a slight feel of chalkiness. I think the slab looking chunks are super thin sheets of feldspar? It is ever so slightly asymmetrical. The "signature" on the bottom appears to be a hand drawn square with a "t" or a cross but it is very hard to tell due to both wear and the rough nature of the clay/medium.