conchoidal
Like broken glass
Conchoidal describes a type of fracture that produces smooth, curved surfaces resembling the interior of a seashell.
The term applies mainly to how certain materials break—glass, obsidian, and flint fracture conchoidally, which made them ideal for prehistoric toolmaking.
The obsidian blade showed the characteristic conchoidal fracture pattern.
Glassy igneous rock
- flintSpark-producing sedimentary rock
- quartzCrystalline silicon dioxide
- chalcedonyTranslucent microcrystalline silica variety
- chertFine-grained siliceous stone
jasper · opal · silica · volcanic · glass · agate · rhyolite · pitchstone
Striking stone to shape tools
- obsidianGlassy igneous rock
- flakingShedding in layers
- lithicsArchaeological stone implements
- percussionSound through impact
knapping · arrowheads · toolmaking · pressure · core · flake · reduction · platform
Smoothly bent, not angular
- rippledMoved in undulations
- smoothWithout roughness or difficulty
- undulatingMoving in waves
- wavelikeResembling ocean swells
scalloped · arcuate · lustrous · glassy · polished · sheen · reflective · translucent
obsidian
Glassy igneous rock
- flintSpark-producing sedimentary rock
- quartzCrystalline silicon dioxide
- chalcedonyTranslucent microcrystalline silica variety
chert · jasper · opal · silica · volcanic · glass · agate · rhyolite · pitchstone · tektite
flintknapping
Striking stone to shape tools
percussion · knapping · arrowheads · toolmaking · pressure · core · flake · reduction · platform · cortex
curved
Smoothly bent, not angular
- rippledMoved in undulations
- smoothWithout roughness or difficulty
- undulatingMoving in waves
wavelike · scalloped · arcuate · lustrous · glassy · polished · sheen · reflective · translucent · gleaming
nautilus
Chambered marine mollusk
- molluskSoft-bodied invertebrate, often shelled
- spiralCurve winding around center
- whorlSpiral arrangement of ridges
gastropod · whelk · marine · logarithmic · chamber · aperture · spire · turbinate · helix