The hard shells have not been permeated by groundwater and not replaced by minerals.

It has high relief, which is the apparent topography exhibited by minerals in thin section as a consequence of refractive index.

The generation of electric signals by minerals under high stress leading to fracture has been confirmed with laboratory experiments.

The main characteristic for all fenites is metasomatic substitution and replacement of primary constituents by K-feldspar minerals.

Cementation of underlying sediments by minerals dissolved in water may occur in a depression.

For example, one of his goals was to find a rich source of white clay, hard to find since it is untainted by other minerals.

(Sugar in particular provides 'empty calories', that is, it provides energy unaccompanied by protein, minerals, or vitamins.)

However, fairly loose materials can get quite hard and erosion resistant when cemented by minerals.

Or, they may be concretions, or accumulated material, formed by minerals coming out of solution as water diffused through rock, he said on a February 9 press conference.

Petrifaction is the replacement of organic matter by minerals in fossilization.