Uncalibrated from Mandarin Stone
http://www.mandarinstone.com/product/_/299/black-riven-slate-tile/?cid=19#.VC4wSmddWSo
A difficult one to price up methinks
http://www.mandarinstone.com/product/_/299/black-riven-slate-tile/?cid=19#.VC4wSmddWSo
A difficult one to price up methinks