Making Red Gold: An Evaluation of Ancient Shell Bead Perforation Techniques

Spondylus shell beads AD –Lithic microdrills After 1200 AD? –no drills…so how were they perforated?

Various uses Several cultures involved Chaquira/Chaîne I –small –regular –known production process Chaîne II –larger –irregular –undefined process

c A.D. Dependent on water Spondylus: possible currency Food: Fish, seabirds, domesticated animals, agriculture

Chert Wood –Oak –Brazilian Teak Copper Shell

Abrasive material –Sand –Pumice Water –Circulates abrasive material

Sand 100x Pumice 500x

SHAFT METHOD

BOW DRILL METHOD

“EPIC FAIL”

Hydrophilic Vinyl Polysiloxane

Coats non-metallic specimen with thin coat of gold palladium Metallic coating necessary so specimen emits secondary electrons

High accuracy 3-D images Shows texture of drilled holes

Primary Material Secondary Material ResultRotations SEM Images ChertNoneDeep hole3,000 ChertSandHole3,500 Chert Sand and water Deep hole2,600 ChertWaterDeep holen/a ChertPumiceHolen/a Chert Pumice and water Holen/a

Chert drill tip Chert drill tip with sand Chert drill tip with sand and water Chert drill tip with water Chert drill tip with pumice

Primary Material Secondary Material ResultsRotationsSEM Images Brazilian Teak NoneNo hole4,000n/a Brazilian Teak SandNo hole 2,000 3,120n/a Brazilian Teak Sand and Water No hole2,100n/a Brazilian Teak PumiceNo hole6,300n/a Brazilian Teak Pumice and Water Very shallow hole 5,000 Medium hole 10,500

Brazilian teak drill with pumice and water

Primary Material Secondary Material ResultsRotationSEM Images Spondylus Shell NoneShallow21,000 Spondylus Shell Water Wide and shallow 16,800 Spondylus Shell Sand Very shallow hole n/a Spondylus Shell Sand and water Very shallow hole n/a Spondylus Shell Pumice Wide very shallow hole 12,600 Spondylus Shell Pumice and water Hole10,500

Spondylus shell drill Spondylus shell drill and water Spondylus shell drill and sand Spondylus shell drill and pumice and water Spondylus shell drill and pumice

Primary Material Secondary Material ResultsRotationSEM Images Red OakNoneNo hole8,000n/a Red OakWaterNo hole8,000n/a Red OakSandNo hole8,000n/a Red Oak Sand and Water No hole8,000n/a Red OakPumiceNo hole8,000n/a Red Oak Pumice and Water Wide shallow hole 8,000

Red oak drill

Primary Material Secondary Material ResultsRotationSEM Images CopperNoneVery small hole 8,000 5,000 CopperWaterVery shallow hole8,000 CopperSandVery shallow hole5,000 Copper Sand and Water No holen/a CopperPumice Almost nothing1,500 Very shallow hole8,000 Copper Pumice and Water Very shallow hole8,000 Almost Nothing8,000 Almost Nothing1,500

Copper drill Copper drill with pumice and water Copper drill and pumice Copper drill and water Copper drill and sand

Efficiency: –Most successful : chert –Mildly successful: teak, shell and copper –Unsuccessful: oak Does this make sense?

Variation in hole-making techniques Different applications of auxiliary material Variation in revolution counts Differences in sharpness & roughness of drill tips

Broader range of drill materials Quantitative data & comparison to SEM images of the Manteño beads

Many different possible techniques Real process = efficient –yet to be discovered Societal significance

Dr. Carter Katie Seither Dr. Miyamoto Drew University Parent and alumni donors to NJGSS John and Laura Overdeck, Jewish Communal Fund, The Ena Zucchi Charitable Trust, FannieMae Foundation, Bristol-Myers Squibb, Vanguard Charitable Endowment Program, and Village Veterinary Hospital

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