from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A clear colorless opal.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A form of opal
from the GNU version of the Collaborative International Dictionary of English
- n. A pellucid variety of opal in globules looking like colorless gum or resin; -- called also Müller's glass.
from The Century Dictionary and Cyclopedia
- n. A pellucid variety of opal, resembling colorless gum or resin.
The sixth is the "hyalite," which has but a glassy or vitreous lustre, and is found almost exclusively in the form of globules, or clusters of globules, somewhat after the form and size of bunches of grapes; hence the name "botryoidal" is often applied to this variety.
Os was already far behind us, and would have been out of sight had not the atmosphere been as clear as hyalite.
These basalts were covered with a mammiform substance, which I vainly sought on the Peak of Teneriffe, and which is known by the names of volcanic glass, glass of Muller, or hyalite: it is the transition from the opal to the chalcedony.