Dolomite snowflake (dolomite ps. after aragonite), twinned

Dolomite snowflake (dolomite ps. after aragonite), twinnedLocale: Roswell, New Mexico Approx dimensions: 2. 5 x 2. 25 x 1. 5" Approx weight: 203g These unusual pseudomorphs of dolomite after aragonite have earned the name snowflake because of their hexagonal shape which is often striated to give the mineral an appearance like a chunky snowflake. Pseudomorph means the mineral initially grew as aragonite, and then through geological processes the aragonite was replaced with dolomite. The new mineral will

Locale: Roswell, New Mexico

Approx dimensions: 2.5 x 2.25 x 1.5"

Approx weight: 203g

These unusual pseudomorphs of dolomite after aragonite have earned the name “snowflake” because of their hexagonal shape which is often striated to give the mineral an appearance like a chunky snowflake. ‘Pseudomorph’ means the mineral initially grew as aragonite, and then through geological processes the aragonite was replaced with dolomite. The new mineral will retain the shape of the original growth. 

With dolomite snowflakes, the aragonite crystal habit is referred to as ‘pseudo-hexagonal’ meaning the crystals that appear hexagonal are actually formed of multiple intergrown crystals (twinned growth). The pseudo-hexagonal crystals grow similar to the arms of its namesake snowflake, forming six symmetric small pointed pie-wedges (you may be able to tell, the boundary between crystals is about halfway between points).

This pseudo-hexagonal crystal habit is common in aragonite! Purple aragonite and sputnik aragonite also have a pseudo-hexagonal habit and get their hexagonal crystal shape from cyclic twinned growth—studied closely you can see similarities with the crystal growth of dolomite snowflakes. This specimen is even more complex; when viewed from the side you see it is actually two twinned dolomite snowflakes, one intersecting the other (twinning on twinning!).

UV reactivity This material reacts well, fluorescing white with orange spots under 365nm UV light. It also has moderately strong phosphorescence of a yellowish-green color.