Formosa is just an old name for Taiwan. Formosa tea just means "Taiwanese tea"; usually the name is associated with oolong, as "Formosa Oolong", as Taiwan is best-known for producing oolong tea.

Most health stores do carry oolong tea.

Oolong, as in oolong tea.

There are many different types of tea produced in Taiwan. Taiwan is best known for oolongs, which are often referred to as "Formosa oolong"; Formosa is just an old name for Taiwan.

Some specific types of oolong produced in Taiwan include Dong Ding and Alishan oolongs. These are both high-grown oolongs, and are called "High Mountain Oolong". Sometimes the teas are classified by their color or oxidation level, with the greener ones called Jade Oolong, and the intermediate ones called Amber Oolong. A darker but mellow and sweet oolong produced in Taiwan is called Bai Hao Oolong. There is another type of very green oolong produced in Taiwan, called Pouchong or Bao Zhong.

These are just a few of the best-known teas produced in Taiwan. There are many different types out there, including green teas and black teas as well.

White tea, Green tea, Oolong tea, and Black tea.