Can Galena Scratch Glass? (ANSWERED)

Galena cannot scratch glass.

In the article that follows, you’ll learn more about galena and glass, and why one can or cannot scratch the other.

Can Galena Scratch Glass? (EXPLAINED)

Hardness of Galena

Whether or not a material can scratch glass comes down to hardness.

Galena, according to the Mohs Hardness Scale, is about 2.5, whereas glass is about 5.5.

Hence, because it is harder than galena, glass will scratch a specimen of galena but a specimen of galena will not scratch glass.

Further, because of Galena’s place on the Mohs Hardness Scale, one cannot always scratch it with a fingernail, but it won’t scratch a copper penny, either.

More About the Moh’s Hardness Scale

The Mohs Hardness Test and Mohs Hardness Scale were devised by German mineralogist Friedrich Mohs in the early 1800s.

The Mohs Hardness Test is one of the most important tools one can use to identify minerals.

The concept of the test is relatively simple: a person uses 10 minerals of distinctly different hardness, ranging from very soft to very hard, to evaluate the mineral in question.

If one specimen can scratch the other, that specimen is harder.

If one were to test galena using specimens commonly found in a standard laboratory Mohs hardness kit, one would expect the following results: galena would certainly scratch talc, with a hardness of one, and gypsum, with a hardness of two.

However, we would not expect galena to scratch calcite, with a hardness of three, and certainly not fluorite, apatite, orthoclase, quartz, topaz, corundum, or at the top, with a hardness of 10, diamond.

What Should We Know About Galena?

Galena is an ore of lead, also called lead glance, and is very easy to identify.

Galena is one of the most abundant and widely distributed (meaning it is found in a large number of deposits in many countries around the world) sulfide minerals.

Primary deposits of galena can be found in Freiberg in Saxony, areas of England, Bulgaria, Sardinia, and the United States.

Notably, in the United States, galena is the official state mineral of three states: Kansas, Missouri, and Wisconsin, and 90% of the United State’s production of lead is mined in the extensive Mississippi River Valley.

It is steel gray with a shiny, metallic luster, and despite its softness, is relatively heavy – in fact, its weight and perfect three-directional cleavage make it distinctive.

The heaviness of galena can be attributed to the fact that lead is its primary element.

Finally, galena is brittle, which is characterized as the mineral’s tenacity.

Galena is also lucratively mined for its silver content.

In some galena deposits, one can find up to 0.5% silver, which far surpasses the main lead ore in revenue.

If there is silver within a galena specimen, it may disrupt the galena’s crystal structure, often causing the galena to have curved cleavage faces.

This is one way a prospector can determine a galena specimen’s potential silver content.

Another way prospectors can determine the presence of galena is that galena weathers easily.

Galena is naturally metallic and shiny, but galena that is exposed to the air or other elements buried in the soil can tarnish rapidly, turning quickly to a dull gray or dull black color.

Galena will weather to anglesite, cerussite, pyromorphite, or another lead mineral, so the presence of these can reveal that galena may be found below the surface of the soil.

While galena is the most useful as an ore for most of the world’s lead production, it is also a significant ore of silver.

Primarily, though, the number one use of galena is in lead-acid batteries that are used to start automobiles and provide standby power supplies for computer networks, communication facilities, and other critical systems due to its property of being a semiconductor.

As the world moves closer to electric and hybrid vehicles, lead, and thereby galena, will be important for use in energy storage systems.

Lead from galena ore is also used to make lead sheets, pipe, shot and low-melting-point alloys.

As a part of history, one of the oldest uses of galena was in the eye cosmetic called kohl.

Kohl was applied by people in Ancient Egypt around the eyes to reduce the glare of the sun and repel flies, which spread disease.

Some historians believe that galena was worked for its lead content as early as 3000 BC.

In North America, indigenous people also used the mineral in cosmetics and widely traded galena throughout the eastern portion of what became the United States.

As a safety note, galena itself is not harmful if handled, but the lead in galena is toxic if inhaled or ingested from dust particles.

One interesting fact about galena is that it could be a part of the “heavy metal snow” scientists discovered falling on the planet Venus!

We know that Venus’ atmosphere is inhospitable.

The surface of Venus is covered by volcanoes that vent superheated gasses into the atmosphere, including gaseous sulphur and lead.

When the gasses are high enough above the planet’s surface to condense into a liquid form, the liquid falls back to the planet’s surface in what researchers at Washington University in St. Louis, Missouri, determined with plausibility was most likely a combination of lead sulfide, or galena, and bismuth sulfide.

Wrap Up

Geologists, prospectors, and science classes can enjoy searching for and identifying galena due to its appearance (steel gray with a shiny luster, unless weathered), weight (heavy due to lead being its primary element), cleavage (geometric), and of course, its place on the Mohs Hardness Scale.