Harney SoHo had this in their Tea flight this weekend, so they posted a description on their blog. I have updated the Tea info for Steepster, but will also post the description here for those still curious parties:
Wuyi Cassia, a cliff tea (Yancha) oolong grows in the Wu Yi mountains in northern Fujian province. Cassia translates to cinnamon, but don’t be fooled by the name! With the oolong’s tight stripe shape and black bloom color, the brewed tea, itself a bright orange color, has toasty, complex flavors.