Black is certainly a possible color in any culture that has dye capabilities (use dark or black sheeps wool, overdye with dark blue). The weave...again there was the capacity to do larger geometric patterns, I know that diamond twill was known, though that is a smaller scale pattern. What is the width? If it is 54" or 60", from 2 1/2 yards you very well could get a rectangular coat, since you are more slender than I am, especially if you perhaps did cuffs and borders from another fabric.