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Flint Rock: Composition and Uses

Prachi Patkar Oct 09, 2020
Flint, a rock that occurs as a constituent of the chalk beds, is made from quartz. It consists of a variety of impurities due to which it seems opaque. This rock was widely used as a weapon in the Stone Age.

Did You Know?

Rocks that are made from quartz having the same structure as that of flint stone are chalcedony, opal, onyx, carnelian, obsidian, agate, and jasper.
A milky to gray-colored quartz containing rock is chalcedony, whereas opal is a mineral comprising quartz too. In chemistry terms, flint rock occurs as a combination of chalcedony and opal, which is a compound consisting of both crystalline as well as colloidal forms of silica.
Flint is undoubtedly one of the hardest rocks. However, it splits like glass when tried to give it shape. This is because its crystal structure varies from that of diamond. Being very hard puts a limit on the processes that could be used to shape it. Shaping the flint by flaking off its chips was a commonly followed method by the Stone Age man.

What is a Flint Rock?

Flint rock is a sedimentary rock consisting of quartz. Quartz, also known as silica, is the compound called silicon dioxide. In this rock, the mineral quartz occurs in the cryptocrystalline form, which implies that quartz grains are too small to be seen without a microscope.


◆ This is a homogeneous rock having a smooth surface.
◆ It is one of the hardest rocks after diamond.
◆ It is porous in nature. However, when the absorbed water evaporates, it becomes more brittle.
◆ This rock fractures like a glass, when hit upon. This implies that it has a conchoidal fracture.

How to Identify a Flint Rock?

Identifying a rock as flint is not a difficult task. This rock sparks when struck with iron-containing objects. This feature can be exploited to identify flint stone.
1. Go to a location that has a large number of rocks available.
2. Try to find rocks that have a strong texture and smooth surfaces. If they have pointed edges, it is a clear indication that they have been sharpened to serve the purpose of a tool.
3. Observe the rock carefully to know its color. If it is a flint rock, its color will be either black, white, maroon, blue, gray, or green. Make sure the rock is dry; if not, wipe it with a cloth.
4. Take a knife and thrust abruptly over the rock multiple times. In case you observe any sparks, then the rock is a flint. If not, take another rock that resembles flint in its color and repeat the procedure.


◆ It gets its color due to the presence of various minerals in its parent rock.
◆ It is considered to be a type of chert. Chert is known to be containing quartz in the microcrystalline form.
◆ It changes its color to gray when heated up.
◆ Flint inherits the physical properties of its parent compound, silica.
◆ It is more opaque than chalcedony.
◆ The outer coating of the rock was retained by the Stone Age men while making tools.
◆ This rock in the heated or calcined form is known as pot boiler.
◆ The freshly crushed rock appears green, blue, maroon, white, brown, black, or gray in color.
◆ It is that form of chert which is a constituent of chalk or marly limestone.
◆ It sometimes displays color banding.

What is Flint Rock Used for?

◆ When flint is impinged on steel, sparks are produced. This is because the particles of iron from steel get ignited due to the presence of oxygen in air. That is why flint was used to ignite fire in the Stone Age period.
◆ It can be polished and decorated to be used in jewelry or as a semiprecious stone.

◆ It has a high degree of sharpness due to which it can be used in developing weapons or tools.

◆ It is sometimes used as a building stone for construction purposes. Its use was quite prone in regions devoid of brick manufacturing units.

Where Is Flint Rock Found?

It is to be noted that this rock is mostly found as a component of chalk deposits. These deposits are found in Denmark, the United Kingdom, Canada, Russia, the United States, Ukraine, Poland, and France. Besides these deposits, it is known to occur in the form of chunks in the continents of North America and Europe too.
Now that we know what the flint rock consists of, it is important to understand that most of the ancient deposits of this rock contain fossils too, along with various minerals.