opal is a hydrated amorphous form of silica. because of its amorphous character, it is classed as a mineraloid, unlike crystalline forms of silica, which are classify as minerals.
Amber is a fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects.
lapis lazuli, or lapis for short, is a deep-blue metamorphic stone used as a semi-precious stone that has been prized since antiquity for its intense color.