Yes, quartz can scratch glass.
Quartz is one of the minerals capable of scratching glass, and this test is one of the ways to determine whether or not a stone is genuine quartz.
To help you understand why quartz can scratch glass so easily, here is what you need to know.
Can Quartz Scratch Glass? (EXPLAINED)
What Is Quartz?
Quartz is the most abundant mineral found in the earth’s crust and it is extremely resistant to weathering, both physical and chemical.
It is a silicate mineral, found in igneous, metamorphic, and sedimentary rocks.
There are many uses for quartz due to its hardness and durability.
With a hardness of 7.0 on the Mohs scale, it is capable of scratching glass, softer stones, and metal.
Due to this hardness, quartz has long been used as an abrasive, being utilized in sandblasting and grinding.
Along with being used as an abrasive, it has also been used in glassmaking, with deposited sands of 100% quartz grains serving as sources of silica sand.
These sands are used often in the production of specialty glass, container glass, flat plate glass, and fiberglass.
Quartz crystals are also commonly used today as crystal oscillators for their ability to vibrate at very precise frequencies.
First developed in the 1920s, they were widely used during WWII, and today, billions are in use in things like televisions, cell phones, clocks, radios, watches, and GPS equipment.
Due to this booming need for quartz, many of the crystals now used in electrical equipment are now grown in labs that simulate the geological processes that create natural quartz.
This ensures that they possess the same properties as natural quartz, but don’t require mass excavation of the natural specimens.
What is Glass?
Glass is often made using sand, limestone, and soda ash.
However, glass can also occur naturally through a number of means.
Most people are familiar with glass formed from volcanic magma known as obsidian.
Obsidian is a common volcanic glass that contains a very high silica content.
Similarly, impactite is glass that is formed from the impact of a meteorite.
Moldavite — found in central and Eastern Europe — and Libyan desert glass — found in the eastern Sahara — are the most well-known examples.
Vitrification of quartz into glass can also occur when lighting impacts sand, which forms root-like hollow glass structures known as fulgurites.
Outside of naturally occurring glasses, there are many types that are manufactured using various materials.
Silicate glass, for instance, has an exceptionally high melting point which is difficult to work with on its own.
Because of this, other substances are often added to lower the melting point and make it less viscous.
While easier to work with in this state, the addition of other compounds also lowers its hardness, making it susceptible to scratches by harder substances.
The average hardness of glass is 5.5 on the Mohs scale, although it can vary depending on the composition.
For instance, natural obsidian has a rating slightly lower at 5.0, whereas Gorilla glass, a chemically strengthened glass used for some smartphone screens, has a hardness of roughly 6.0.
Can Quartz Scratch Glass?
Yes, quartz can naturally scratch glass as it is harder and higher on the Mohs scale.
You can even test this for yourself at home with a small piece of glass and a quartz stone.
This can also be a way to tell whether or not the quartz you have is genuine, as artificial ones are often made from glass or plastic, both of which are nowhere near as hard as true quartz.
Scratch tests are simple to conduct and all you will need is a piece of test glass and the point of a quartz stone.
Press the quartz firmly against the glass plate and scratch it across a small area.
When you examine it you should be able to see an etched line in the glass caused by the harder quartz.
You may even use a fingertip or fingernail to feel the etched line if you’re unable to see it.
Glass, on the other hand, cannot scratch anything about a 5.5 on the Mohs scale, as it is too soft.
It can, however, scratch stones below 5.5, such as malachite, fluorite, calcite, gypsum, and talc.
Anything harder, such as quartz, moonstone, peridot, tourmaline, topaz, and ruby cannot be scratched by glass, but can instead scratch glass.
Scratches On Your Phone
If you pick up your phone and examine the screen closely, you may notice tiny scratches in the glass.
These aren’t from your keys, loose change, or plastic key chains, instead, they can come from dust, grit, and sand that contain tiny particles of quartz and other hard minerals.
This is especially true if you’re fond of bringing your phone with you to the beach or other locations where sand is prevalent.
Sand can easily scratch away at your phone’s glass screen, and while it’s not necessarily damaging, it can be irritating.
While you may think that tempered glass screen protectors can help, many still have a hardness lower or equal to that of quartz, making them susceptible to scratching, even if many protectors claim that they are scratch-resistant.
Although tiny quartz particles can be difficult to avoid sometimes, due to their tiny size, you can mitigate the risk by leaving your phone in a safe area if you know you’ll be in an area near sand and other quartz particulates.
Quartz is one of the most abundant minerals on earth, and it is one that can easily scratch glass with very minimal effort.
If you have a piece of quartz in your home, you can test this out for yourself on a small sheet of glass to see firsthand how mineral hardness works.