It was the first mineral to have been discovered with rubidium as an essential constituent.

It is the essential constituent of the universe and is at the basis of all the activity of the creation.

The presence of melilite is an essential constituent in some rare igneous rocks, such as olivine melilitite.

Quartz is an essential constituent of granite and other felsic igneous rocks.

Sterols are essential constituents of cellular membranes in human, animals and plants.

Quartz is an essential constituent of granite, and abounds in rocks of all ages.

An essential constituent appeared to be a substance called epidermal growth factor.

His failed attempt is an essential constituent of the play's tragedy.

If our diet is deficient in any of these essential constituents, we will in time become ill because our metabolic systems cannot function properly.

However, this direct communication is an essential constituent of an effective procedure.