"Block" is the plastic imitation turquoise that is sometimes referred to as recon turq or reconstituted or reconstructed. It's NOT ground up anything.

The picture shows blocks of man made imitation turquoise seen in a supply shop in Bangkok in 2005. Most of this "block" turquoise was made in the US. Imitation "block" stone is made to look like many different stones including lapis, malachite, rhodonite, sugilite and dyed coral.