Biconical drilling is an ancient technique used to perforate stone, bone, shell, and other hard materials by drilling from both sides of an object, producing a hole that is wider at the surfaces and narrower in the middle. It is a diagnostic feature in archaeology, especially for beads, pendants, and other ornaments.

🌍 Definition

• Biconical Drilling: A method of creating a perforation by drilling from opposite sides of an artifact.
• Resulting Hole: Hourglass-shaped (wider at both openings, tapering toward the center).
• Tools Used: Stone drills, reed drills with abrasive slurry (sand, quartz), or metal points in later periods.

🔑 Archaeological Contexts

• Beads & Pendants:
  • Common in Neolithic and Bronze Age ornaments.
  • Biconical perforations are diagnostic of hand-drilling techniques.
• Stone & Shell Artifacts:
  • Shell beads often show biconical holes from reed drills with sand abrasives.
  • Hard stones like carnelian or turquoise required repeated drilling from both sides.
• Diagnostic Feature:
  • Archaeologists identify biconical drilling by examining perforation cross-sections.
  • Helps distinguish ancient hand-drilling from modern machine drilling (which produces straight cylindrical holes).

📚 Importance in Anthropology

• Technological Insight: Reveals the ingenuity of early craftspeople in working hard materials.
• Cultural Identity: Distinct drilling styles can be linked to specific cultures or regions.
• Comparative Value: Highlights differences between prehistoric drilling methods (biconical, bow-drill, tubular drilling) and modern techniques.
• Material Culture: Beads and ornaments with biconical holes often carried symbolic or social significance (status, trade, ritual).

In short: Biconical drilling is the ancient practice of perforating artifacts from both sides, producing hourglass-shaped holes that are diagnostic of hand-drilling techniques in beads, ornaments, and tools.