January’s Mineral: Snow [H2O(s)]

Posted by : Emily | On : January 1, 2014

Photo By Craig Sheppard

A mineral is defined as a naturally occurring, inorganically formed, homogeneous solid with a definite chemical composition and an ordered atomic arrangement – therefore, snow can be considered a mineral! Given the season, and the amount of snow that has graced the eastern seaboard over the passed few weeks, we felt it was fitting to have snow as the first ‘mineral’ of the month for 2014.

Snow is composed of crystalline particles of ice (matted together or alone) forming hexagonal stars, plates, or needles. The exact six-sided shape is dependant on formation temperature and moisture and it is therefore very unlikely to find two snowflakes to appear exactly alike. A non-aggregated snowflake often exhibits beautiful six-fold radial symmetry due to the crystalline structure of ice.

Snow crystals form when tiny, supercooled, cloud droplets freeze and grow in a supersaturated environment. The droplet grows by diffusion of water molecules in the air onto the ice crystal surface where they are collected. These crystals are able to grow to hundreds of micrometres or millimetres in size at the expense of the water droplets by a process known as the Wegner-Bergeron-Findeison process. Eventually, the ice crystal will become large enough to fall through the cloud and toward the ground, possibly growing larger along the way by colliding with other ice crystals through collision coalescence, aggregation, or accretion.

The classic stellar crystals shown in the photo above had to develop between -12 and -16 degrees celsius. For more information on the different types of snowflakes and their formation, please visit SnowCrystals.com.

Happy New Year!

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