Pu-erh tea

„Depending on the desired product and speed, from quickest and tightest to slowest and loosest, pressing can be done by a large heavy stone, carved into the shape of a short cylinder with a handle, simply weighs a bag of tea down onto a wooden board. The tension from the bag and the weight of the stone together give the tea its rounded and sometimes non-uniformed edge. Due to the manual labor involved, this method of pressing is often referred to as: "hand" or "stone-pressing", and is how many artisanal pu'er bǐng are still manufactured.“

„Pos­si­bly the most neb­u­lous of tea’s qual­i­ties are ascribed to 茶氣 [chá qì] — a tea’s “energy.” Most read­ers will prob­a­bly be famil­iar with at least some of the wide rang­ing effects it is attrib­uted with. Prac­ti­cally any phys­i­cal or men­tal stim­u­lus out­side of the mouth, nose, and throat falls into the realm of cha qi.“