1. A twin crystal formed by the intergrowth of two crystals of the same mineral in a symmetrical arrangement.
Usage: mineralogy; geology
2. A dark spot or blemish on a mineral or gemstone.
Usage: mineralogy

Examples

• The geologist identified the macle as a feldspar twin crystal.
• Macles are common in quartz specimens found in alpine environments.
• The diamond's value was reduced due to a visible macle near its surface.
• Under the microscope, the macle showed the characteristic symmetrical pattern of intergrown crystals.
• Collectors often seek out specimens with well-formed macles for their aesthetic appeal.