Note:  Do not rely on this information. It is very old.

Jargon

Jargon, or Zircon, a rare mineral, in which Klaproth (1789) first indicated the presence of the element zirconium, the compound consisting of a silicate of that metal Zi Si 04. It forms crystals somewhat resembling diamonds but heavier; specific gravity 45, and not as hard. It is frequently coloured blue, green, or orange, the latter being the variety most prized as gems. Jargon is found in a number of localities, but Ceylon is the chief source of the mineral.