Opal which has no play of colour and is of no value.
- ‘They usually consist of a very thin opal slice sandwiched between a glass or quartz top and a potch, basanite, jade, or black onyx bottom.’
- ‘One potential use of common or potch opal is for the production of cristobalite for use as a dental and jewellery investment.’
- ‘It often serves as an excellent dark backing for black opals which normally have a thin segment of precious opal naturally formed on a potch backing.’
Late 19th century: of unknown origin.
We take a look at several popular, though confusing, punctuation marks.