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Flint as a Gemstone
Flint is a very durable material that accepts a bright polish and often occurs in attractive colors. It is occasionally cut into cabochons, beads, and baroque shapes for use as a gemstone. It is also used to produce tumbled stones in a rock tumbler. Most people have heard of a gem material called “jasper”. Jasper is an opaque variety…
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Flint as a Source of Fire
Another important property of flint is its ability to generate sparks of hot material when it is struck against steel. This property allows flint to be used as a fire-starter. Skilled people can use a piece of flint, a piece of steel, and a little tinder to quickly start a fire. Early firearms, such as…
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Neolithic Flint Miners
Perhaps the most impressive story about flint is that of the ancient mining complexes that were built in what is now England during Neolithic times. These excavations began about 4000 BC and continued until the widespread use of metals about 2,000 years later. One flint mining complex of particular note was Grime’s Graves located near Brandon, England.…
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Alibates Flint Quarries
In the area that is now the Texas panhandle, Native Americans discovered an area where weathered flint littered the ground. This flint was weathering out of a dolomite beneath the thin soil cover. These people discovered that fresh, unweathered flint of high quality could be obtained by digging down a few feet. From about 13,000 years ago…
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Flint Ridge Quarries, Ohio
One of the most important localities for flint in eastern North America is Flint Ridge in eastern Ohio. Native Americans discovered this deposit and produced flint from hundreds of small quarries along the ridge. This “Ohio Flint” occurred in distinctive colors and was treasured by Native Americans. They travelled hundreds of miles to collect it…
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The Preferred Tool-Making Material
Flint has been used by humans to make stone tools for at least two million years. [1] The conchoidal fracture of flint causes it to break into sharp-edged pieces. Early people recognized this property of flint and learned how to fashion it into knife blades, projectile points, scrapers, axes, drills, and other sharp tools. They…
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What is Flint?
Flint is a hard, tough chemical or biochemical sedimentary rock that breaks with a conchoidal fracture. It is a form of microcrystalline quartz that is typically called “chert” by geologists. Flint often forms as nodules in sedimentary rocks such as chalk and marine limestones. The nodules can be dispersed randomly throughout the rock unit but are often concentrated in distinct layers. Some rock…
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Uses of Dolomite
Dolomite and limestone are used in similar ways. They are crushed and used as an aggregate in construction projects. They are kiln-fired in the manufacture of cement. They are cut into blocks and slabs for use as a dimension stone. They are calcined to produce lime. In some of these uses, dolomite is preferred. Its…
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Metamorphism of Dolomite
Dolomite behaves like limestone when it is subjected to heat and pressure. It begins to recrystallize as the temperature rises. As this occurs, the size of the dolomite crystals in the rock increases, and the rock develops a distinctly crystalline appearance. If you examine the photo of granular dolomite, you will see that the rock…
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“Dolomite Rock” and “Dolostone”
Some geologists are uncomfortable using the word “dolomite” for both a mineral and a rock of the same composition. They instead prefer using “dolomite rock” or “dolostone” when speaking of the sedimentary rock and “dolomite” when speaking of the mineral. Although these terms simplify communication and improve accuracy, many geologists continue to use the word “dolomite” for both the mineral…