Carbuncle Stones how he might finde;
And where to find wise men and trewe,
Which would for his interest pursue,
In seeking all the Worlde about,
Plenty of Carbuncles to find out;
For this he took so mickle thought,
That his fatt flesh wasted nigh to naught.[253]
It is scarcely necessary to add that the poor parson never realized his dream, but the story shows how popular was the belief that carbuncles or rubies shone with their own light.
A luminous or phosphorescent stone, which has been named the Bologna stone, is the subject of a treatise published by the physician Mentzel in 1675.[254] The writer describes various experiments made to test the peculiar qualities of this mineral, which is partly a radiated or crystalline sulphate of barytes, and phosphoresces when calcined. It was sometimes called the “lunar stone” (lapis lunaris), because, like the moon, it gave out in the darkness the light it received from the sun. Mentzel also relates that the stone was first discovered, in 1604, by Vincenzio Casscioroli, an adept in alchemy, who believed that it would be a great aid in the transmutation of the baser metals into gold, on account of its solar quality. The place of its occurrence was Monte Paterno, near Bologna, where it appeared in the fissures of the mountain, after torrential rains.