Druse, encrustation – Aggregate of crystals coating a surface or cavity, usually found in geodes

March 13, 2023
by

Common examples: azurite, celestine, calcite, uvarovite, malachite, quartz

Celestine

In geology, druse refers to a coating of fine crystals on a rock fracture surface or vein or within a vug or geode.

Druse of uvarovite from the Urals; size: 18.3 cm × 13.1 cm × 2.0 cm (7.2 in × 5.2 in × 0.8 in) Uvarovite Locality: Saranovskii Mine (Saranovskoe), Saranovskaya (Sarany) Village, Gorozavodskii area, Permskaya Oblast’, Middle Urals, Urals Region, Russia (Locality at mindat.org) Size: large cabinet, 18.3 x 13.1 x 2.0 cm UVAROVITE Garnet This large plate of the rare uvarovite garnet varietal is the largest and finest I personally know of or have seen. Since 1832 when they were found at this, the Type Locality for the species, this garnet has been the standard of excellence for a green garnet species. Named after Count Sergey Semeonovich Uvarov (1786-1855), Russian statesman and scholar, President of the Academy of St Petersburg (1818-1855) – according to MINDAT. For the collector, this is thus a historical specimen and a beauty. This plate is museum-sized, and rich in quality as well as having that size. Uvarovite crystals do not grow so large as other species of garnet, especially from this locality where most crystals are sub-mm in size and 2mm crystals are considered noteworthy. This specimen has crystals to a whopping 5.5 mm – DOZENS if not hundreds of them. Although there is some damage, it is relatively minor and lost amidst hundreds, literally, of bright and reflective pristine crystals on this plate. This specimen was in the Richard Kosnar collection since it came out of an old Russian collection in 2001. When I first saw it, my mouth dropped. I had no idea such a piece existed. (Rob Lavinsky irocks.com)
Pink dolomite druse with yellow calcite crystals, Ben Hogan Quarry, Lawrence County Zinc District, Arkansas; size: 14.9 cm × 8.5 cm × 3.7 cm (5.9 in × 3.3 in × 1.5 in) Calcite, Dolomite Locality: Ben Hogan Quarry (Black Rock Quarry), Black Rock, Lawrence County Zinc District, Lawrence County, Arkansas, USA (Locality at mindat.org) Gemmy, silky crystals of calcite on salmon-colored dolomite, recently mined in Arkansas. The light-golden calcites are nicely transparent, lustrous, and measure to 2.6 cm. 14.9 x 8.5 x 3.7 cm

See also

References

Tags:

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.