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Why is the name rare earth a misnomer?

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A line graph showing electron probability distributions for gadolinium, with separate curves for 4f, 5s, 5p, 5d, and 6s orbitals. The x-axis shows distance from the nucleus in atomic units and the y-axis shows probability P2(r). — rare-earth element Electron probabilities, P²*(r)*, for the 4f, 5s, 5p, 5d, and 6s electrons of gadolinium.

The term "rare earth" is a misnomer because these chemical elements are actually quite abundant in the Earth's crust, falling into the 50th percentile of elemental abundances.12

The name originated in the 18th century due to two historical factors:
* Terminology: When these elements were first discovered, they were found as components of complex oxides, which were referred to as "earths" at that time.1
* Perceived Scarcity: These minerals appeared to be scarce when they were first identified, leading to the designation "rare earths".1

In reality, these elements exist in many workable deposits globally, and they are not rare in the sense of being difficult to find. While their concentration levels in specific ores can be low—often requiring efficient mining and processing techniques—they are widely distributed and essential to modern technology.12