This is a very
old and common
structure. In ancient time and in antiquity, it seems to have
sometimes been used for fire. In modern times it has been used for lunar
halo i.e. the faint
and yellow mist that sometimes encircles the moon.
As a pharmaceutical sign it was used to signify scrupulum, scruple, a small stone used as a weight, and an ancient Roman weight and apothecary's weight of 1/24 ounce. It was also the name given to the smallest coin in the Roman Empire.
Compare with the mystical rock carved sign in Group 47, and with in Group 42.