I love telling people that most tea bags are literally made from dust. People think I’m using the word to indicate the incredibly low quality (which is correct), but dust is actually an official term in the tea lexicon. 

Here’s a bag of Tea Silver Cloud “CTC Dust” grade tea. I found this when I was in Coonoor in Southern India in May 2013.

Highfield Tea Estate (top right) and many other estates in Southern India and elsewhere in the world, produce several grades of CTC (crush, tear, curl) tea. It ranges from coarse to very fine. CTC is a method of manufacture where tea leaves are torn up several times through a series of machines. This tea is then left to oxidize (turn color from green to black) and then fired (baked). 

The James Norwood Pratt Tea Dictionary has an entry for dust too.