In the world of crystals, jasper typically refers to opaque stones and agate refers to translucent stones. However, ancient jasper seems to have included chalcedony and the references to clear, green jasper were probably addressing chrysoprase. Jade was also included as a jasper.
The name jasper means a stone that has spots or speckles. It traces back to jaspre, an old French word that is a variation on an Anglo-Norman word, jaspe. There is also the Latin word, iaspidem, which is derived from the Greek word, ἴασπις which is also connected to the Hebrew word ישפה yashpeh.
Jasper has a very practical history. For instance, green jasper was used as a drill for making bows in Mehrgarh, Pakistan in the New Stone Age between 4th and 5th millennium BC.