Sometimes called Venetian Glass, most colors are manufactured but the mineralized ones are hand-mixed. Regular sizes and surfaces. Less expensive than smalti but still up there, especially the mineralized variety. This includes the whole range of ceramic tiles available locally at tile stores and home centers. They can be glazed or unglazed.
Unglazed porcelain is a wonderful material for mosaics although the color selection is limited.
If you are working from large tiles, you may want to first snap them into strips using a standard tile cutter or wet saw then proceed with your hand tools. Look around for bargain leftovers and discontinued patterns.