As an adjective trigonal

is symmetrically triangular.

As a noun chladniite is

(mineral) a colourless trigonal mineral.

As nouns the difference between mineral and chladniite

is that mineral is mineral while chladniite is (mineral) a colourless trigonal mineral.

As nouns the difference between biscuit and biccy

is that biscuit is (lb) a cookie while biccy is (informal|british) a biscuit.

As nouns the difference between silicate and okenite

is that silicate is while okenite is (mineralogy) a silicate mineral associated with zeolites, having the chemical formula (casi₂o₅·2h₂o).

As nouns the difference between mineral and okenite

is that mineral is mineral while okenite is (mineralogy) a silicate mineral associated with zeolites, having the chemical formula (casi₂o₅·2h₂o).

As nouns the difference between cation and photoion

is that cation is (brazil) while photoion is (chemistry) a cation produced through photoionization.

As nouns the difference between photoionization and photoion

is that photoionization is while photoion is (chemistry) a cation produced through photoionization.

Photoelectron is a coordinate term of photoion.

As nouns the difference between photoelectron and photoion

is that photoelectron is (physics) an electron ejected from the surface of a material by the photoelectric effect while photoion is (chemistry) a cation produced through photoionization.

Photoionic is a related term of photoion.

As a noun photoion is

(chemistry) a cation produced through photoionization.

Photoionize is a related term of photoion.

As a verb photoionize

is (physics) to cause, or to undergo photoionization.

As a noun photoion is

(chemistry) a cation produced through photoionization.