摩氏硬度，又译莫氏硬度，是一种利用矿物的相对刻划硬度划分矿物硬度的标准，该标准是德国矿物学家腓特烈·摩斯（德语：Friedrich Mohs）于1812年提出的。

摩氏硬度标准将十种常见矿物的硬度按照从小到大分为十级，即（1）滑石、（2）石膏、（3）方解石、（4）萤石、（5）磷灰石、（6）正长石、（7）石英、（8）黄玉、（9）刚玉、（10）金刚石。具体鉴定方法是，在未知硬度的矿物上选定一个平滑面，用上述已知矿物的一种加以刻划，如果未知矿物表面出现划痕，则说明未知矿物的硬度小于已知矿物；若已知矿物表面出现划痕，则说明未知矿物的硬度大于已知矿物。如此依次试验，即可得出未知矿物的相对硬度。

The Mohs scale of mineral hardness is a qualitative ordinal scale that characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science, some of which are more quantitative. The method of comparing hardness by seeing which minerals can visibly scratch others, however, is of great antiquity, having been mentioned by Theophrastus in his treatise On Stones, c. 300 BC, followed by Pliny the Elder in his Naturalis Historia, c. 77 AD. While greatly facilitating the identification of minerals in the field, the Mohs scale does not show how well hard materials perform in an industrial setting.