On Tuesday, March 1, 2022, at 7:00 p.m., we’ll be having our monthly meeting virtually, featuring…
The Mineral Ice: Collecting Frost Crystals
with Johan Maertens!
Members, watch your email for connection information!
The Oxford English Dictionary defines a mineral as “a solid inorganic substance of natural occurrence.” By this definition, water ice is clearly a mineral, but the fact that ice melts at room temperature has caused many to dismiss it as collectible. Still, we have all learned from an early age that “no two snowflakes are alike,” so clearly there is something interesting to be learned in trying to understand the causes of the various growth habits of water when forming the mineral ice. This talk grew out of the author’s fascination with the varieties of ice crystals that grew on the windows of his New Jersey home in the winter of 2011.
Frost, a variety of ice, forms when water vapor transitions to a solid, ice, without a liquid phase. Many of the frost crystals in this presentation were ‘collected’ by the author from the north facing windows of his house. The most common type of frost is irregular; however, window frost often forms hexagonal plates and columns.
The crystals are three dimensional and sometimes are seen as elaborate patterns. Overall aggregate growth depends on the growth of each face, based on temperature and supersaturation levels, and one should also consider the type of surface (to which it is affixed). Common habit changes occur at -4ºC, -10ºC, and -22ºC.
Johan will show a wide array of detailed images, revealing the intricate patterns of frost crystals and polycrystalline aggregates. The images include stellar or broad branched plates, perfectly hexagonal sectored plates with distinct ridges, and polycrystalline stellar dendrites. Fernlike stellar dendrites occur when many side branches are formed. By documenting the various growth habits of frost with photographs, one can ‘collect’ this common mineral without having to refrigerate your display cabinet.