The magic key to identifying mineral materials – Mohs hardness pen

Mohs hardness pen introduction

In the world of minerals and rough stones, hardness is a vital property. From the brilliant light of gemstones to the durability of industrial materials, hardness plays a key role. And there is a small but powerful tool that can help us easily measure the hardness of minerals and gemstones, it is the Mohs hardness pen.

Mohs hardness pen is a convenient testing tool designed and manufactured according to the Mohs hardness standard. The tip of the Mohs hardness pen is made of materials with different hardness levels. The standard hardness minerals from 1 to 10 are: 1 talc, 2 gypsum, 3 calcite, 4 fluorite, 5 apatite, 6 orthoclase, 7 quartz, 8 topaz, 9 corundum, 10 diamond (as shown in Figure 1). By performing a scratching experiment on the surface of the material being tested, the hardness range of the material can be judged based on whether scratches are left.

Figure 1   Mohs Hardness pen

The usage of Mohs hardness pen is simple and easy to understand

1. Preparation: Before using the Mohs hardness pen, you need to ensure that the surface of the material to be tested is clean, flat, and free of oil, dust or other impurities. This can ensure the accuracy of the test results.
2. Choose a suitable hardness pen: Mohs hardness pens usually have a variety of hardness levels to choose from, the most common ones are from 1 to 9. Based on the initial estimate of the hardness of the material being tested, choose a hardness pen that may be suitable. It is generally recommended to start with a pen with a lower hardness.
3. Scratching operation: Hold the hardness pen at an angle of about 30° – 60° to the surface of the material being tested, apply pressure gently and move slowly to scratch a line about 5 – 10 mm long on the surface of the material (as shown in Figure 2). Note that the pressure should be even during the scratching process and the speed should not be too fast.
4. Observation results: After the scratching is completed, carefully observe the scratches on the surface of the material. If there are no obvious scratches on the surface of the material, it means that the hardness of the material is greater than the hardness of the hardness pen tip; if there are clearly visible scratches, it means that the hardness of the material is less than or equal to the hardness of the hardness pen tip.
5. Determine the hardness range: If the hardness pen you choose for the first time does not leave a scratch, you can try to use a pen with a higher hardness to scratch again; conversely, if scratches are left, try a pen with a lower hardness. Through this step-by-step trial method, the hardness range of the material can be finally determined.

Figure 2   Usage of hardness pen

Mohs hardness pen has a wide range of applications

In the field of jewelry identification, the Mohs hardness pen is a powerful assistant for appraisers. Different gemstones often have different hardness. Through the test of the Mohs hardness pen, the authenticity and quality of the gemstone can be preliminarily judged. For example, the hardness of diamond is 10, which is the hardest substance in nature. If a Mohs hardness pen with a hardness of 9 is used to scratch the surface of a material suspected to be a diamond, if no scratch is left, then the material is likely to be a real diamond; but if a scratch is left, then the material is a fake.

In geological exploration, geologists often need to perform hardness tests on the collected ore samples. The Mohs hardness pen is small and portable, which is convenient for geologists to quickly determine the type and characteristics of ore in the field. Different ores have unique hardness characteristics due to their different compositions and structures, which is of great significance for geologists to analyze geological structures and find mineral resources.

In industrial production, Mohs hardness pens also play an important role. In industries such as metal processing and plastic manufacturing, the hardness of materials directly affects the quality and performance of products. By using Mohs hardness pens to test the hardness of raw materials and semi-finished products, material quality problems can be discovered in a timely manner to avoid product defects and production accidents caused by material hardness not meeting requirements.

Mohs hardness pen has become an indispensable tool in the field of material testing due to its simple, easy-to-use, accurate and reliable features. Whether it is professional scientific researchers, jewelry appraisers, industrial producers, or geology enthusiasts, they can all benefit from the use of Mohs hardness pen. It is like a magic key that helps us open the door to the mystery of material hardness, allowing us to better understand and use various materials. If you are also curious about the world of materials, you might as well own a set of Mohs hardness pens and start your journey of exploration!

Figure 3   Hardness pen packaging