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Sincosite

Named after its first noted occurrence and type locality at Sincos, Peru. Sincosite occurs in vanadium rich phosphatic sedimentary environments often associated with Minyulite, Fluellite, and Wavellite. Crystals are thin to thick plates with square to rectangular outlines. Also occurs as scaly crusts, botryoidal masses, and in rosette-like aggregates. Colors can range from grass green to bright green and olive-brown to brassy brown within the same deposit. Rare worldwide. Large, well formed crystals of Sincosite can be found at the Ross Hannibal mine in the Black Hills of South Dakota, USA.
Ref.Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/sincosite.pdf
- Formula
- Ca(V4+O)2(PO4)2ยท5H2O
- Crystal System
- Tetragonal
- Crystal Habit
- Scaly, Platy, Aggregates
- Cleavage
- Perfect, Distinct, Poor
- Luster
- Vitreous - Metallic
- Color
- green, yellowish green, olive green, brownish green
- Streak
- light green
- Class
- Tetragonal
- Fracture
- Brittle
- Hardness
- 1-2
- WebMineral
- View Sincosite
- Mindat
- View Sincosite
Sincosite from Ross Hannibal mine, Lawrence Co., South Dakota, United States

- Special Info
- The 1996 discovery of Sincosite by Tom Loomis
Single, square, tabular, grass green crystals from 0.5mm to 3mm with white divergent sprays of Minyulite to 3mm.
The Ross Hannibal discovery by Tom Lomis of Dakota Matrix in 1996 was the finest Sincosite the world had ever seen. Sincosite was first found in the early 1920's in the phosphatic black shales of Sincos, Peru, thus the name. It was also found in the 1890's at the Ross Hannibal mine, but was thought to be Torbernite. Much later a specimen from Bryn Mawr college was reanalyzed and the true identity was made. In 1996, the Sincosite deposit was rediscovered during open pit mining the old Ross Hannibal workings. The Ross Hannibal was mined in a phosphate-rich zone within the lower Cambrian Deadwood fm. For additional information and a full account of this discovery please reference the May/June 1990 issue of the Mineralogical Record.
Sincosite from South Rasmussen Ridge mine, Soda Springs, Caribou Co., Idaho

- Special Info
- The 2010 discovery of Sincosite by Tom Loomis.
Sincosite crystals from 0.5mm to 1.5mm as singles and rosettes black shale phosphate rock of the Phosphoria Formation associated with bright blue to green and black Phosphovanadylite-Ca, a new mineral approved by the IMA in 2012. See Phosphovanadylite-Ca for more information.
Sincosite from Union Carbide mine, Wilson Springs, Garland Co., Arkansas, United States
Square tabular crystals of very rare Sincosite crystals to 0.2mm in a 4x4mm and other scattered crystals all on drusy Quartz. Don Owens was the mine geologist at this mine and this was self-collected at the T-Orebody by him.