Let’s talk about the Mohr scale

Hello, fellow paw lovers,

When you work with gemstones, how do you communicate the hardness of a mineral? You use the Mohr scale, which is named after Friedrich Mohr.

Mohr Hardness Level 10

Of course we know the hardest material on earth is diamond, which has a Mohr scale of 10, the maximum. BTW, diamond is not native to the earth surface. It’s formed by meteorites hitting the earth, and the strong force, pressure, and heat turn the carbon on earth into diamonds. 

Nowadays, we can manufacture diamonds in the lab by using similar mechanisms. They are lab-created diamonds; for example, moissanite is a lab-created diamond. The word moissanite is a trade mark. 

I’ll update the post with a picture of the moissanite late here.

Mohr Hardness Level 9

Another very common hard gemstone we often encounter is corundum (Al2O3), which has a Mohr scale of 9. Sapphires, rubies (Al₂O₃:Cr³⁺), and Alexandrites are all corundum. They have a hardness level of 8, which is harder than almost everything in daily life. That’s why high-end watches often advertise that they have a sapphire glass cover. They use the word sapphire to assimilate the hardness and strength of sapphire. However, in fact the cover is made of sapphire crystal, which is not natural sapphire. Sapphire crystal is made by heating and crystallizing aluminum oxide. 

So why do the corundums have different colors? The sapphires have trace amounts of iron, titanium, cobalt, lead, chromium, vanadium, magnesium, boron, and silicon. Rubies have a trace amount of chromium, and Alexandrite has a trace amount of Beryllium. 

Mohr Hardness Level 8

Next we come to Topaz, which has a Mohr scale of 8.

You would think Topaz is blue, right? Actually, it looks quite similar to quartz in nature. It often has a yellowish tint. Natural blue topaz is very rare in nature. It is often heated to bring out the beautiful blue color. 

Mohr Hardness Level 7

Quartz!

Finally, we come to Mohr scale 7. 

What is quartz?

Quartz can refer to collections of gemstones that have similar composition; just as corundum is a collection for rubies, sapphires, and alexandrites. 

The main composition for quartz is silicon oxide, SiO4. And you are right, sand is a mixture of minerals, and most of them are silicon oxide. 

What are the different colors of quartz? 

Purple: Amethyst (Fe³⁺) 

Trace amounts of Fe³⁺ in SiO4 give the crystal a purplish tint. That is amethyst. The best quality of amethyst comes from Brazil, especially from the Rio Grande do Sul area. Their amethyst is dark purple, and the crystals can be very large. 

Amethyst is believed to have healing power and is associated with the third eye chakra, and is the birthstone for people born in February. 

Yellow citrine (Fe²⁺) 

Trace amounts of Fe²⁺ in SiO4 give the crystal a yellowish tint. That is citrine. The best quality of citrine also comes from Brazil, especially from the Rio Grande do Sul area. 

Citrine is believed to bring abundance, optimism, and happiness, and is the birthstone for November. 

Mohr Hardness Level 6

Peridot

I purchased these Peridots for my mom, whose birthday is in August. These peridots are native to the United States. They are from Arizona, the biggest producer of peridots. As you can see, the edges are rounded. They are very smooth. That is because they are often found near the river, and the gemstones have already been touched and perfected by nature. I love how they look, so beautifully shining with a perfect green Smith apple color.

Tanzanite 

Tanzanite is very unique. The name is after the country it’s found, Tanzania. It’s the birthstone of December. You will often see them in the shop as blue, but in fact the colors range from milky lavender to purplish blue. The darker and the more blue, the higher the price. In my opinion, I love the rocks for their natural beauty but not for a price tag.

Titanite (CaTiSiO5)

Titanite, despite its name, is not actually very hard. The name comes from the fact that it contains titanium. BTW, currently, I have a titanium keychain at Paw4ever. I consider them to be much higher quality than normal keychains. They are also quite expensive to buy by themselves. And I like the warm grayish metal tone. Anyway, the real titanite, in fact, is quite brittle; some pieces of my titanite shattered during my move across the states. The yellowish tone is also from Fe2. Oh, it looks like I will also post an article on the chemistry side of gemstones. Stay tuned.

Mohr Hardness Level 5

Opal

Opals are for very gentle and elegant souls. They are not for rough handlings. I purchased my opals from Australia. They are small but extremely beautiful gemstones but also extremely brittle. That is why you never see opal being shaped into multiple facets like diamonds and sapphires. They are always polished into cabochons. 

We do not usually discuss the hardness level under 5 when we talk about gemstones because there are too many things that are below 5. Gemstones are precious because of the qualities they possess, they are strong, resistance to pressure and beautiful. In fact, their beauty is a result of their strength. 

Love y’all! 

Please comment below to let me know if you have any questions or requests.

Have a blessed day!