No, glass is not a mineral, because its atoms are not arranged in a specific orderly manner.
And for some reason, this is a hotly debated topic.
To understand the answer to this question (and also understand why there are so many thoughts on the topics) we think the best way is to pass over the opinions you’ll find in forums and start first with a quick discussion of what makes a mineral a mineral, and then see how glass fails to falls within that “mineral test.”
Why Is Glass A Mineral? (Or Not?)
First, What Makes a Material a Mineral?
To answer this question, we have to first confirm what it means for a substance or material to be a mineral. Something can be called a mineral if can pass all of the following:
- it is naturally formed (meaning it forms in nature and humans didn’t have to help it)
- the material is a solid
- inorganic (meaning not alive), though a mineral can be formed by an organic process
- the material has a chemical composition that is always the same
- atoms are arranged in an orderly manner (crystalline)
The substance has to be all of these things in order to be called a mineral.
Now That We Have The Test, Let’s Answer the 5 Questions:
First question: Is glass naturally formed, meaning without the aid of humans?
In general, most glass that we have in our houses is man-made, and does not occur in that form (flat and clear) naturally.
However, glass does occur in nature, without the assistance of humans, formed by volcanos, impact craters, and lightning strikes.
Obsidian is a form of glass that is made without the aid of humans, for example.
Folks may argue that glass fails right out of the gate because the glass that most people are thinking of when asking this question (like windowpanes) is man-made in a factory.
Others may argue that glass formed in nature passes this question, and man-made glass does not.
We take the position that since glass exists in nature, it passes this part of the test.
Next question: Is glass a solid?
This is actually not an easy question to answer either, and leaves even more room for debate than the question of whether glass passes the “naturally formed” test.
Glass feels solid. You hold it in your hands, and it does not move.
However, there is evidence to support the contention that that glass is not a solid and is actually a liquid, while others will argue that the evidence leads to the conclusion that it is neither.
Glass is what is called an “amorphous” solid, a material that is in between the state of being a liquid or a solid. (source)
The reason: the molecules making up the glass are not organized and orderly like they are in a usual solid structure.
Since glass fails the “mineral test” in a later question, it is not necessarily worthwhile to pick this one completely apart.
Next question: Is the material inorganic?
Yes, the material is inorganic. It is not alive or made up of living organic matter.
Next question: does glass have a consistent chemical composition?
Glass is SiO2 (silicon dioxide). Manufactured glass may not be purely SiO2, but most agree that it doesn’t disqualify glass on this point.
However, others will argue that glass does not have a specific chemical formula because of all the various chemicals and products that are added into it to make it at a factory.
There is plenty to debate here. But we’ll table the debate because the glass question can be put to rest without much debate in the next section of the test.
Next question: are the atoms arranged in an orderly manner?
No, the atoms in glass are not arranged in an orderly manner.
As discussed above in the section about whether or not glass is a solid, we know that glass is an amorphous solid.
This means that while the molecules are connected in a structure, those connections are completely disorderly.
Is Glass a Mineral? The Answer is….NOPE
Since glass does not have an consistently orderly structure, it fails the test to be called a mineral, regardless of what you think about the other questions (occurring in nature versus man-made, solid vs liquid).
Are There Minerals In Glass?
Yes, there are often many minerals in glass.
The methods (and recipe) to make glass varies from industry to industry, and company to company.
One glass may contain a certain mineral, while another glass (or even something formed out in nature) may be composed of others.
The following minerals are often used in the manufacture of glass:
- calcium carbonate
Most glass is made mostly of silica (like sand, quartz), soda (soda ash, natron, plant ashes), and lime (chalk, limestone). These are melted together at a high temperature and then cooled.