As a materials science expert with a focus on metallurgy, I can tell you that the concept of the "hardest metal on Earth" can be a bit misleading because hardness is not a fixed property and can vary depending on the specific conditions and treatments a metal undergoes. However, when we talk about metals in their natural state and their inherent hardness, we often refer to the Mohs scale of mineral hardness, which is a qualitative scale.

The Mohs scale ranges from 1 (talc, the softest) to 10 (diamond, the hardest naturally occurring material). On this scale, chromium is one of the harder metals, with a Mohs hardness of approximately 8.5. However, it's important to note that tantalum and osmium are also very hard metals, with reported hardness values that are similar to or slightly higher than chromium.

When it comes to man-made alloys, the situation is different. Some of the hardest metals are not pure metals but rather alloys, which are mixtures of metals with other elements to enhance their properties. For example, tungsten carbide, which is an alloy of tungsten and carbon, is extremely hard and is often used in applications like drill bits and cutting tools.

It's also worth mentioning that the term "hardest" can be subjective and context-dependent. For instance, in terms of resistance to scratching, diamond is the hardest, but when it comes to resistance to deformation, other metals might be considered "harder."

In conclusion, while chromium is one of the hardest metals, the title of the "hardest metal on Earth" can vary based on the specific criteria used to define hardness and whether we are considering natural metals or man-made alloys.

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The Strongest Natural (Non-Alloy) Metals: Tungsten, Titanium, and ChromiumTungsten has the highest tensile strength of any natural metal, but it's brittle and tends to shatter on impact.Titanium has a tensile strength of 63,000 psi. ... Chromium, on the Mohs scale for hardness, is the hardest metal around.read more >>