The answer to this question is that it depends on what the “gravel” is.
Why Is Gravel A Mineral? (Or Not?)
What Is Gravel?
In general, gravel doesn’t refer to one specific kind of material or substance. Instead, the term “gravel” is usually the word we use to indicate rocks of a certain size, larger than sand and pebbles, up to even boulder size.
Usually people refer to the kind of gravel by the size of the pieces, either by the average measurement of the stones or (fine, medium, coarse).
Gravel exists naturally in the world, and it is also produced commercially, when large sandstone, basalt, or limestones rocks (among others) are crushed into smaller pieces.
What Are The Qualifications To Be Considered A Mineral?
There are legal and judicial definitions for what constitutes “a mineral.”
For this article, we are going to focus on the geological qualifications. There are five characteristics that a substance must have in order to be considered a mineral:
one: The substance must exist in nature.
two: The substance must be a solid (at normal temperatures on Earth).
three: The substance must be entirely inorganic. An organic substance is usually one that contains many carbon to hydrogen bonds (C-H).
four: The chemical composition of the substance needs to be consistent throughout the named material.
five: The internal structure is orderly and consistent throughout.
Is Gravel A Mineral? (The Analysis)
Gravel can be considered a mineral when the gravel is made up of a substance that is considered a mineral.
Just analyzing “gravel” as a substance is not specific enough, because gravel can be made up of many types of substances, or the gravel may contain more than one kind of substance.
Let’s look at gravel made of basalt, as an example.
First, basalt is a material that exists on Earth, and is not human-made, though a human could probably make it. (meets the requirements)
Second, basalt is a solid. At normal temperatures, it is not a liquid or a gas. (meets the requirements)
Third, basalt is inorganic. It is made up of many different substances, but none of those substances are organic compounds. (meets the requirements)
Fourth, basalt is not chemically consistent throughout the substance. Basalt is a volcanic rock, formed by the rapid cooling of basaltic lava. It’s chemical composition varies, depending on what other substances were present in the melted rock as it moved towards cooling.
Basalt may contain a lot of silicon dioxide (like quartz), or very little in other cases. It may contain a lot of aluminum, or very little. It may contain a lot of feldspar, sodalite, and other minerals, or very little.
Since basalt as a substance is not chemically consistent, it does not meet the requirements to be a mineral.
Finally, while basalt is a solid, it is also a mixture. The materials that make up the substance are mixed into the solid, rather than bonded to each other chemically.
This means that the structure of the material changes as you move from one kind of substance to the next.
Since basalt is not structurally consistent, it does not meet the requirements to be a mineral.
Finally, because basalt does not meet all five geological requirements, basalt is not considered a mineral.
Could Gravel Be A Mineral?
Yes, this is entirely possible.
If the small stones in your gravel are a mineral (like if your gravel was entirely made of silicon dioxide), then you could call that gravel a mineral.
In general though, if the substance is fully a mineral, it is probably too valuable to be used as a gravel. It would be used to higher level manufacturing and decoration.
It would not be used to stabilize your driveway.
Could Gravel Be A Mineral For the Purposes of A Landowner’s Mineral Rights?
Yes, this is entirely possible. However, whether the rock on a piece of property qualifies as a mineral for the purposes of a landowner’s rights is going to be location, city, county, state, and/or country specific.
Is Gravel A Compound?
Maybe. This is going to depend entirely upon what kind of material the gravel is made up of.
A compound is formed when two or more substances bond to each other chemically.
If the gravel is made up of basalt, the answer is going to be no, as the substances that make up basalt are melted together, but not bonded to each other chemically.
If the gravel is made up of 100% silicon dioxide, then the answer is going to be yes, the gravel is a compound.
Silicon dioxide is formed when silicon and oxygen bond to each other chemically. There are no other substances mixed in with it floating around or otherwise that make up this substance. Because it is a compound, any gravel made up of silicon dioxide will also be considered a compound.
Is Gravel A Mixture?
Again, the answer to this is maybe.
A mixture is a material composed of more than one substance, where the substances are physically in the same space without being chemically bonded to each other.
In many cases, gravel is a mixture due to the way it has been created. Rock is dug, harvested, blasted out of the quarry, transported to a crusher, and reduced to a certain size of stone.
In these cases, especially when the rock is intended for construction, it is rare that attempts are made to filter or purify the rock down to one kind of substance.
The result is that the gravel will likely contain many substances, some obvious, while others are not.
The only way that gravel would not be a mixture is if the rock was 100% an element or compound without impurities. It is rare that such a substance would be turned into gravel or used as we use gravel.
Interested in learning about other common substances, and whether they’d be considered a mineral? Check out our mineral articles about: sand, concrete, dirt, hydrogen, seawater, sugar, glass, and charcoal.