micromounts

Very small specimens

Scorodite
scorodite micromount

Photo by Yaiba Sakaguchi

This scorodite specimen is only 8mm long, but it is very pretty. It is from the Drakelands Mine, Plympton, Tavistock District, Devon, England, UK. It gets its name from the Greek σκορόδιου = “Scorodion”, which means it smells like garlic when heated. Scorodite can also be called Arsenic Sinter. It comes from the oxidation of arsenopyrite or other arsenic-bearing species.

Chemical Formula: Fe3+AsO4·2H2O

Source: https://www.mindat.org/min-3595.html

Cuprosklodowskite

This is from the Musonoi Extension mine, near Kolwezi, Shaba Province, Zaire, from the collection of Michael Scott. The Rruff Project used single-crystal X-ray diffraction to confirm the identity of the cuprosklodowskite. It is basically Sklodowskite (named after Marie Sklodowska Curie) that contains copper.

More info: http://rruff.info/cuprosklodowskite/display=default/

Pyrope Garnet

This is a special type of garnet called pyrope garnet. The name comes from the Greek pyro, meaning fire. Pyrope and other members of the aluminum part of the garnet group have a higher specific gravity and hardness, and are usually red. Calcium garnets like the previously mentioned andradite and uvarovite are the ones that are usually green and have a lower hardness and specific gravity.

Pyrope garnet is difficult to distinguish from almandine, but pyrope usually has fewer flaws and inclusions. However, garnet jewelry is usually almandine garnet because almandine is much more common and inexpensive.

If you would like some pyrope garnet it can be found nearby in Kansas, all around the Nemaha Uplift (or Nemaha Ridge), which is in the area between Salina and Manhattan, and extending south into Oklahoma. Basically, garnets are found anywhere near previous volcanic activity. The one pictured is from Apache County, Arizona. They are also found in Africa and other places. For lots and lots of information about this particular specimen, see its page on the RRUFF here.

Snowflakes for the First Day of Winter

Electron and Confocal Microscopy Laboratory, Agricultural Research Service, U. S. Department of Agriculture.
Electron and Confocal Microscopy Laboratory, Agricultural Research Service, U. S. Department of Agriculture.
Electron and Confocal Microscopy Laboratory, Agricultural Research Service, U. S. Department of Agriculture.
Electron and Confocal Microscopy Laboratory, Agricultural Research Service, U. S. Department of Agriculture.
Electron and Confocal Microscopy Laboratory, Agricultural Research Service, U. S. Department of Agriculture.
Electron and Confocal Microscopy Laboratory, Agricultural Research Service, U. S. Department of Agriculture.
Electron and Confocal Microscopy Laboratory, Agricultural Research Service, U. S. Department of Agriculture.
Electron and Confocal Microscopy Laboratory, Agricultural Research Service, U. S. Department of Agriculture.

We usually feature quartz crystals or fluorite crystals, but today’s crystal is somewhat different. To celebrate the first day of winter, here are some photos of snowflakes taken with a Low Temperature Scanning Electron Microscope (LT-SEM). The photos were taken by members of the Electron and Confocal Microscopy Laboratory, Agricultural Research Service, U. S. Department of Agriculture. From top to bottom, left to right, there are some needle crystals, a snow crystal coated in rime, a hoar crystal, a common snow crystal, a snowdrift from St. Louis Creek, a close-up of packed snow, a side plane crystal, and the traditional dendritic snow crystal. Suddenly I understand why there are so many different types of snow. More photos of snowflakes here.