Initially thought to be of two species, tetrahedral and cubic, it was later confirmed that both samples conformed to the 23 point group of the isometric crystal class and typically exhibits cubic, octahedral, or pyritohedral forms although euhedral crystals are rare.

Evidence cited includes the fact that some samples exhibit encapsulated insects, a feature readily explained by the presence of a viscous resin.

This modest sample nevertheless exhibits substantial size variation, with molars at both the largest and smallest end of the modern gorilla ranges of variation.

For example, two samples of natural rubber may exhibit different durability, even though their molecules comprise the same monomers.

These samples might then exhibit almost perfect first order phase changes at the melting temperature.

Also, because of the potential temporal variability in the toxicity of effluents, a negative test result with a particular sample does not preclude the possibility that samples collected at some other time might exhibit chronic toxicity.

The principle of operation of photoelastic modulators is based on the photoelastic effect, in which a mechanically stressed sample exhibits birefringence proportional to the resulting strain.

Optically active samples, such as solutions of chiral molecules, often exhibit circular birefringence.

The sample chosen should exhibit the characteristics and variations in attitude, behaviour, purchasing capability (etc) that are relevant to the line of enquiry being undertaken by the market research (and to its marketing objective).

And the sample should exhibit these characteristics and variations in much the same proportions as in the total population from which the sample has been drawn.