1. plural of macle; twin crystals of a mineral that are intergrown in a symmetrical pattern
Usage: mineralogy; geology
2. plural of macle; a dark spot or blemish on a diamond or other gemstone
Usage: gemology

Examples

• The geologist examined the macles in the quartz specimen under the microscope.
• Macles are common in feldspar crystals found in igneous rocks.
• The diamond's value was reduced due to several visible macles.
• Twin macles form when two crystal structures grow together in a specific geometric relationship.
• Mineralogists study macles to understand the formation conditions of crystals.