Which mineral is known for having a hardness rating of 9 on the Mohs scale?

The mineral known for having a hardness rating of 9 on the Mohs scale is sapphire. The Mohs scale is a scale from 1 to 10 that rates minerals based on their ability to scratch one another, with talc being the softest (1) and diamond being the hardest (10). Sapphire is a variety of corundum, with a hardness of 9, making it extremely durable and suitable for various applications, including jewelry and industrial uses.

Sapphire's high hardness means it can withstand scratches from many other materials, which contributes to its popularity in adornments that are intended to be worn regularly. This characteristic is a key reason why sapphire is often sought after in engagement rings and other formal jewelry pieces.

Other minerals listed, such as quartz, diamond, and topaz, have different hardness ratings. Quartz has a hardness of 7, topaz has a hardness of 8, and diamond, while being the hardest mineral, has a rating of 10. Understanding the Mohs scale and the hardness of different minerals helps in various fields including geology, gemology, and materials science.