from The American Heritage® Dictionary of the English Language, 5th Edition.
- adjective Having a microscopic crystalline structure.
from The Century Dictionary.
- Indistinctly or imperfectly crystalline: used of a mineral whose structure is so fine that its crystalline character is not apparent to the eye, or which is semi-amorphous; also of a rock, or of its base, in which no definite character is discernible in the constituent particles, even with the microscope. See
from the GNU version of the Collaborative International Dictionary of English.
- adjective (Geol.) Indistinctly crystalline; -- applied to rocks and minerals, whose state of aggregation is so fine that no distinct particles are visible, even under the microscope.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- adjective mineralogy Whose
crystallinenature only becomes apparent at high levels of magnification.
- noun mineralogy A rock of this kind.
from Wiktionary, Creative Commons Attribution/Share-Alike License
The many semi-precious stones which have a quartz basis (such as the varieties of waxy or cryptocrystalline chalcedony which is largely quartz in a very minutely crystalline condition) are often even tougher than the clear crystallized quartz.
Chalcedony (SiO2) — A light-colored cryptocrystalline variety of quartz, transparent to translucent, and with a waxy luster.