Stone Type: Sedimentary

Sandstone grinding stone

Sediments like sand, silt, and clay are produced by erosion of bedrock outcrops and accumulate in layers on land and under the oceans.  The lower parts of these layered deposits become subjected to intense pressure and high temperatures.  This compacts the sediments, forces out the water, and minerals such as silica precipitate into the spaces between particles.  The particles are cemented together to form sedimentary rock.

Chert

Chert is a sedimentary rock composed of microcrystalline quartz.  It usually formed by the precipitation of silica into other sedimentary rocks, occurring as nodules or layers in limestone.  It forms when tiny organisms extract pure silica from ocean water and use it as body armour or skeletons.  When the organisms die, their skeletons dissolve and form a siliceous ooze, which eventually precipitates, coalesces, and recrystallises as the surrounding limestone rock is formed. 

Handaxe UAE

Acheulean Handaxe

Handaxe, UAE

Acheulean Handaxe

Angostura point

Angostura Point

arrowhead fetish

Arrowhead Fetish

Aterian Point 1

Aterian Point

Aterian point 2 17 Jul 2023

Aterian Point

Bead blank, Khambhat

Bead Blank

Bipolar core, USA

Bipolar Core

Bipolar core, Indiana

Bipolar Core

Blade, Beidha

Blade

Blade from Pakistan

Blade

Blade, Jebel al-Faya UAE

Blade

Blade, Europe AIA

Blade

Burin, France

Burin

Sweetwater Biface

Caddo Biface

Clovis point, Indiana

Clovis Point

screenshot (7) copy 2

Clovis Point

Eccentric, Guatemala

Eccentric

Elk River 1

Elk River Point

Elko point, NV

Elko Point

End scraper, France

End Scraper

Etley point, Missouri

Etley Point

Fan scraper, Jordan

Fan Scraper

Arrowhead 7 UAE

Fasad Point

Flint

Flint occurs as nodules or seams in chalk. It is a folk classification within the general category of chert.  Chert nodules form when tiny organisms extract pure silica from ocean water and use it as body armour or skeletons.  When the organisms die, their skeletons dissolve and form a siliceous ooze, which eventually precipitates, coalesces, and recrystallises as the surrounding limestone rock is formed.  When the material precipitates into hollows such as crustacean or mollusc burrows, nodules are formed.  Fine-grained varieties of chert are some of the best stones for flintknapping because of the exceptionally high silica content.

Handaxe St Acheul

Acheulean Handaxe

Handaxe UK, Iver AIA

Acheulean Handaxe

Handaxe France

Acheulean Handaxe

Handaxe UK, giant ficron 2023

Acheulean Handaxe

Handaxe with shell fossil

Acheulean Handaxe

Handaxe AIA ambiguous label

Acheulean Handaxe

Handaxe, Broom, England

Acheulean Handaxe

Handaxe, Swanscombe

Acheulean Handaxe

Handaxe twisted cordate Manchester uni

Acheulean Handaxe, ‘s-twist’

Arrowhead, England, AIA

Barbed and Tanged Arrowhead

Arrowhead Ireland AIA

Barbed and Tanged Arrowhead

Blade, Thetford England AIA

Blade

Blade, Indirect percussion Denmark 3

Blade

Blade, indirect percussion, Denmark 2

Blade

Blade indirect percussion glossed

Blade

Blade core indirect percussion France

Blade Core

Burin, Kostenki 12

Burin

Burin, Norway

Burin

Ukraine cobble core Oleksandr

Core

End scraper, Kent, AIA

End Scraper

End scraper, Kostenki 17

End Scraper

Engraved flint nodule 1, Israel

Engraved Nodule

Eolith core 1

Eolith Core

Eolith core 2

Eolith Core

Silcrete

Silcrete is a duricrust formed when quartz grains are cemented together by dissolved silica. In fine-grained silcrete, quartz sand grains appear to be ‘floating’ in the matrix of silica, while other varieties are composed mostly of quartz grains. The latter varieties are a form of orthoquartzite, or silicified sandstone. Silcrete is a very common source of stone for tools made by Aboriginal people in Australia, but it can also be found in other parts of the world, such as South Africa and the Congo Basin. The flaking quality of silcrete can often be improved by heat treatment.

Bidirectional core, Mithaka 1

Bidirectional Core

Flake blank core Mithaka

Core on Flake

Flake blank core, Mithaka

Core on Flake

Core Tool 2 Mithaka

Core Tool

Core tool 1, Mithaka

Core Tool

Flake, siret arris

Flake

Grinding dish twin groove Charleville

Grinding Dish

Horsehoof core re-do

Horsehoof Core

Horsehoof core Mithaka straight edge

Horsehoof Core

Horsehoof core ARPA with resharpening scars

Horsehoof Core

Horsehoof core Mithaka FB

Horsehoof Core

Horsehoof core Mithaka classic

Horsehoof Core

Horsehoof core Widi

Horsehoof Core

Horsehoof core bifacial Mithaka 1

Horsehoof Core

Horsehoof core, Australia (2)

Horsehoof Core

Kimberley point, lithic casting lab

Kimberley Point

Macroblade core on flake, Mithaka

Macroblade Core on Flake

Microblade Hunter Valley 1

Microblade

Microblade core, Mithaka

Microblade Core

Backed microlith Coola Kangerong

Microlith

Microlith 1 Murramarang

Microlith

Elko point Mark's work

Modern Art, Mark Moore

Multiplatform core, Anaiwan

Multiplatform Core

Pirri SA long

Pirri Point

Quartzite

Quartzite is rock composed of quartz sand grains. Silicified sandstone, or ‘orthoquartzite’, consists of sand grains fused together with silica. It resembles hardened sugar and some varieties have excellent flaking qualities. Metamorphosed sandstone, or ‘metaquartzite’, is formed when the sandstone is altered by heat and pressure, blending and distorting the individual grains.  Metaquartzite is exceptionally tough but can be percussion flaked into durable stone tools.

Cleaver, Sudan

Acheulean Cleaver

Handaxe Quartzite England AIA

Acheulean Handaxe

Handaxe, Tanzania

Acheulean Handaxe

Handaxe, Algeria

Acheulean Handaxe

Handaxe, Western Sahara

Acheulean Handaxe

Handaxe Morocco

Acheulean Handaxe

Handaxe, Morocco

Acheulean Handaxe

Handaxe on a flake

Acheulean Handaxe

Cobble chopper, Niger

Bifacial Core

Hammerstone, USA

Hammerstone

Hammerstone, Anaiwan 1

Hammerstone

Tosawihi hammerstone 7

Hammerstone

Kimberley Point, ex WA Museum

Kimberley Point

Levallois nubian core quartzite egypt

Levallois Core

Lupemban foliate 1, no end thin

Lupemban Foliate Biface

Lupemban foliate 2, end thinned

Lupemban Foliate Biface

Leilira macroblade knife

Macroblade (Leilira) Knife

Macroblade with bees wax 1

Macroblade Point

Macroblade NT ARPA donation

Macroblade Point

Spheroid, Olduvai Gorge

Spheroid

Hafted spear, Arnhem Land

Stone-Tipped Spear

Waisted axe, Australia

Waisted Axe

Mudstone

Mudstone is a fine-grained sedimentary rock formed from clays or muds.  It consists mostly of silicate minerals.  It differs from sandstone in having individual grains too small to see without a microscope.  Mudstone differs from shale by its lack of parallel layers.  Mudstone can be sufficiently silicified to be flaked into tools, and some varieties are suitable for heat-treatment.  It tends to have a slightly rough or coarse texture, and occurs in a variety of colours depending on the trace minerals.

Blade metased Qld 1

Blade

Dolomite

Dolomite is a sedimentary rock often occurring in association with limestone.  It forms by replacement of the calcite in limestone with the mineral dolomite.  Limestone with more than 50% of the dolomite mineral is referred to as dolomite rock.  Dolomite rock is usually yellowish brown or brown in colour.  Dolomite rock can be percussion flaked but is generally unsuitable for refined tools.  It is easily pecked and ground into sculptures and other objects.

Arm ring, Mali

Stone Arm Ring

Sandstone

Sandstone is a sedimentary rock composed of sand grains (often quartz) bound together within a matrix of silt- or clay-sized particles.  The stone’s abrasive qualities make it ideal for grinding stones, although the relative lack of silica in the matrix makes it difficult to flake in a controlled way.  Harder and fine-grained varieties of sandstone have long been shaped by direct and indirect percussion flaking into building stones, or shaped by grinding into sculptures.  Silicified sandstone can be flaked into tools if there is sufficient silica content in the matrix.

Axe grinding grooves, France

Axe Grinding Grooves

Grinding dish, Australia

Grinding Dish

Grinding stone, Anaiwan 1

Grinding Stone

Grindstone blank Mithaka

Grinding Stone Blank

Muller 1

Muller