Dictionarium polygraphicum. Lapis lazuli.

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
LAPIS LAZULI, a mineral stone of a blue colour. Pliny and Ditseorides reckon it a sand; Agricola, a mineral found in the veins of the earth; but in reality it is a mere stone, called by way of excellence Lapis, or Lapis Lazuli.

When this stone is perfect, it is studded with little specks, or stars of gold; and to be good, it should be able to resist the fire and smoak, and to come out of them with new lustre.

It is found in mines of gold, silver, and copper, and also in pits of marble; which last is that now generally in use.

Lapis Lazuli is distinguished into 3 kinds: the first is called old rock, which is pure, smooth, a fine blue, with beautiful yellow streaks, like veins of gold, which yet are frequently no more than veins of pyrites.

The second, which is called the new rock, and is stuffed with common stones; its colour is weaker, and its price lower: These two kinds come to us from Persia and Siam.

The third kind is brought from the mountains of Auvergne in France. This kind is mixed with the common rock whence it is dug, is of a pale blue, and sprinkled with greenish spots, with veins of pyrites.

This, when sufficiently charged with spots of green, is sold for the Armenian stone.