Dictionarium polygraphicum. Jeat

Dictionarium Polygraphicum:
Or, The Whole Body of Arts Regularly Digested.
Vol II.
London: Printed for C. Hitch and C. Davis in Pater-noster Row, and S. Austen in St. Paul's Church Yard. MDCCXXXV.
1735
Jeat, sometimes called black amber, is a mineral, or a fossilc stone, extremely black, formed of a lapidific, or bituminous juice in the earth, in the manner of coal: it works like amber, and has most of its qualities.

It abounds in Dauphins; but the best in the world, is said to be produc'd in some of the northern parts of England.

There is also a factitious jeat made of glass, in imitation of the mineral jeat.

This is drawn out into long hollow strings, which are cut, and form'd at pleasure. It is much us'd in embroideries, and in the trimmings of mourning, and may be made of any colour, tho' they are usually black and white.