The use of precious opal as a gemstone so dominates the awareness of opal in the community that it is seldom realised that there may be other uses for opaline silicas outside the lapidary industry. Opal in the massive translucent form of potch or common opal is a potentially useful material commercially. It is a reactive form of silica which is easily comminuted, and could be used with advantage in many areas, such as the ceramic industry, where flint and quartz are now used. The major factor in preventing its use is a supply in sufficient quantity.

One potential use of common or potch opal is for the production of cristobalite for use as a dental and jewellery investment. The quantities needed in this use are not large, and may well be available from the Australian opal fields. As a side issue, this would give some extra income to miners who were not finding much 'colour', as the potch is at present discarded.

Cristobalite for this purpose is usually made from quartz by calcination at very high temperatures. However, it has been shown (R0242) that opal, especially opal-A potch, is readily converted to cristobalite at about 1100°C.

An unusual use of potch or opal of no commercial value is shown in, where it has been fixed to a garage door for ornamental purposes!