A variety of opal which reflects a reddish glow in a bright light; called also fire-opal.

A variety of opal which becomes transparent on absorbing water; = hydrophane, n.

a variety of opal; = oculus mundi, n.

A variety of opaque or partly translucent opal which absorbs water upon immersion and becomes transparent.

A variety of the opal, opaque, bluish-white, porcelain-white, pale yellowish or reddish.

Mineralogy. = resin opal n. at resin, n. adj.compounds 2. Obsolete.

a mineral said to become translucent or to show colour when warmed, esp. a form of opal with this property, made by impregnating hydrophane with…

An inferior variety of opal harder and more opaque than common opal.

a variety of opal showing flame-coloured internal reflections; (also) a stone of this.

a variety of opal showing red or yellow internal reflections; (also) a stone of this; cf. fire opal n. at fire, n. int.compounds 2a.

An impure variety of opal, containing admixtures of alumina, sesquioxide of iron, and lime.

A variety of opal containing lime and alumina as impurities.

an impure opal containing iron oxide and having the colour of yellow jasper.

= jasper-opal n. at jasper, n.1 compounds 3.

a brownish-yellow variety of common opal with a resinous lustre.

a yellow to brown variety of common opal with a pitchy lustre; cf. resin opal n. at resin, n. adj.compounds 2.

= jasper-opal n. at jasper, n.1 compounds 3.

a form of opal with a banded structure of different colours.

The Oriental or noble opal. Also attributive.

= 4.

(see quot.).

In full potch opal. Opal that has no play of colour and is of little or no value; (also) a flat colour characteristic of this; potch and (or with) c…

An opal characterized by closely spaced specks of colour; such opals collectively. Also: the appearance of such an opal.

a variety of opal containing dendritic markings like those of moss agate.

A black opal occurring as a nodule coated with sandstone or opal dirt (the characteristic form at Lightning Ridge, New South Wales).