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The Mohs Hardness Scale


The 10 Minerals On The Mohs Scale

The Mohs scale was devised by Friedrich Mohs (French) in 1812.

One uses the Mohs scale by testing an unknown mineral against one of these standard minerals. The mineral that scratches the other is the harder of the two minerals.  That is Mohs hardness is the resistance to scratch by a harder mineral.

The Mohs scale is strictly a relative scale and not an absolute scale.  In terms of absolute hardness, diamond is actually 4 times harder than corundum.

The Mohs Hardness scale range from 1 to 10.  Diamond has a Mohs hardness of 10 and is the hardness of all known mineral.  Talc is the lowest with a scale of 1.

Practical Applications

Hardness test can be practical in the field when you want to know whether your specimen mineral is harder than the standard one you are using.

A Quartz Crystal Scratching A Nephrite Jade Rod

I always carry with me a Quartz crystal (hardness 7) in the field.  This is useful for me to differentiate between rough Jadeite Jade (hardness of 7) and rough Nephrite Jade (hardness of 6).  If the specimen can be scratched then it is not likely to be a Jadeite Jade.

Warning: This is a destructive test.  For jade carvings, this test is useful when you want to differentiate between Jadeite and Nephrite.  Choose an inconspicuous place and scratch it.  If it leaves a dent then it is not likely that the jade sculpture you are holding is of Jadeite material.

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I am a Graduate Gemologist trained at the Gemological Institute of America (GIA) in New York City, USA. I hold an MBA degree from Cranfield University, United Kingdom, and a Bachelor degree in Mathematics. My earlier profession was a banker until I found jade in Myanmar (Burma) in the early 90s. I have traveled to the fabled Hpakan Jade mines, and Mogok, the world’s famous rubies and sapphires mines in upper Burma, with my second son. Three of my children are also Graduate Gemologist, GIA, NYC and they deal in diamonds, gemstones and jade. 我是在美国纽约市的美国宝石学院(GIA)接受过培训的宝石研究学家。 我拥有英国克兰菲尔德大学的工商管理硕士学位和数学学士学位。我以前的职业是银行家,直到90年代初我在缅甸接触到玉石。我曾经和我的次子一起去过缅甸上流传说中的哈帕翡翠矿山和莫谷矿山, 莫谷矿山是世界上著名的红宝石和蓝宝石矿山。我的三个孩子都是纽约市GIA毕业的宝石研究学家, 他们专门处理钻石,宝石和玉石.


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