A term applied to the lustre of certain minerals, usually on crystal faces parallel to a good cleavage, the lustre resembling that of pearls,
Archive | N RSS feed for this section
A species of clay mineral, identical in composition with kaolinite, from which it differs in certain optical characters and in atomic structure.
Pole of the horizon vertically below the observer; hence the point on the celestial sphere diametrically opposite the zenith.
A birthmark or mole. 1 A pigmented tumour in the skin. 2 A patch or swelling in the skin composed of small dilated blood vessels,
A name for a group of animal diseases in Africa caused by trypanosomes. Also fly disease, tsetse fly disease.
In higher mammals, a horny plate of epidermal origin taking the place of a claw at the end of a digit.
A small steel rod tapering at one end, used to drive the head of a nail beneath the surface of the timber. Also nail set.