buhrstone, also burrstone /bûrˈstōn/

1. A variety of quartz, containing many small empty cells, which give it a roughness of surface particularly adapted for millstones
2. A millstone made of this

• twilights
• twilight sleep
• twilight sleeps
• twilight zone
• twilight zones
• twilit
• 'twill
• twill
• twilled
• twillies
• twilling
• twills
• twilly
• twilt
• twin
• twi-natured
• twin axes
• twin axis
• twin bed
• twin-bedded
• twin beds
• twin birth
• twin births
• twin-born
• twin brother