A brand new type of ice made from very cold steel balls.

A new type of ice called medium-density amorphous ice has the same density as liquid water, so studying it could help us understand the strange behavior of water at low temperatures.

Researchers have discovered a completely new form of ice. Ice is amorphous, meaning it doesn’t have a well-organized crystalline structure, and it can help unravel the mysteries of liquid water.

We already knew about two types of amorphous ice: high density and low density. There was a gap in the middle, and the researchers thought there was no way to make medium-density amorphous ice, or MDA. But when Christoph Salzmann of University College London and his colleagues placed ordinary ice, which has a hexagonal crystal structure, into a glass with steel ball bearings cooled to -200°C (-328°F), the shear forces created by the shocks created MDA.

“It was one of those Friday afternoon experiments where you just do it and see what happens,” says Salzmann. “Naively, you think that nothing will happen, you will just break the ice into smaller pieces. But, to our great surprise, something did happen.”

The fine white powder produced by the experiment had a density just between two other known forms of amorphous ice, almost exactly the same density as liquid water. This led the researchers to speculate that it could be water in what is known as the glassy phase, which is a type of matter that continues to behave like a liquid even at extremely low temperatures – glass can appear solid for short periods of time, but at longer scales time it flows like a viscous liquid.

Liquid water, no matter how ordinary it may seem, holds secrets when cooled to extremely low temperatures. Based on the gap between low-density and high-density amorphous ice, researchers have previously suggested that supercooled water could actually exist simultaneously in two different liquid phases, with one floating on top of the other, but the existence of MDA casts doubt on this idea.

“It’s not crystalline like normal ice, the face of ice you know, and the density is the same as liquid water, so the big question is, what kind of substance is that?” Salzmann says. “I’m sure if we can figure out what MDA is, we’ll understand liquid water a lot better.”

MDA may also be an important component of the outer solar system’s icy satellites. These strange worlds are experiencing intense shear forces due to the gravity of their host planets, which could create the right conditions for MDA to form. The researchers also found that when this ice was heated, it gave off a huge amount of heat, which could have a huge impact on the geological activity of these worlds.