I just this minute visited Wiki to check which was released first,
Pentangle's "Cruel Sister" or Led Zep 3..

Too my amusement, this is the first thing you will see on the Wiki home page -

"From today's featured article

A metalloid is a chemical element that has properties in between those of metals and nonmetals.
There is no standard definition of a metalloid,
nor is there agreement as to which elements are appropriately classified as such.
Despite this uncertainty, the term remains in use in chemistry literature."

..now doesn't that sound uncannily familiar....?????