Rock and a Hard Place? Not for Elaterite: The Mineraloid that Defies Rigidity

Mineral Matters #178

Today, an enigmatic “mineral” for this week’s Facebook Mineral of the Week Group’s selected theme of minerals that form in a botryoidal habit.

I’m pushing the boundaries a bit here. Elaterite is technically a mineraloid, not a valid mineral. But it certainly fits the botryoidal bit! And the chalcopyrite is trying hard to conform too!

Elaterite, also known as "elastic bitumen", "mineral caoutchouc", or "wurtzilite", is a mineraloid with properties that blur the line between rock and rubber. Its name is said to come from the Greek ελάστιχος (elastic).

Elaterite is primarily a hydrocarbon mixture, although the exact mix can vary. It can contain other elements like sulphur and oxygen. It’s consistency varies, ranging from soft, elastic, and sticky like rubber, to hard and brittle. This variation depends on its composition and exposure to the elements.

Below: Chalcopyrite and elaterite, Albion Mine, Cilfynnydd, Pontypridd, Wales. Width of view 5.5mm.