Cueva Alfredo Jahn, Venezuela
Speleothems: large pale blue spots on erroded walls
Frequency: Extremely Rare
Other geologic settings: In black lignitic shales containing pyrite
First description of cave occurrence: Forti P. & Urbani P.E. 1996. I nuovi minerali di grotta scoperti nella ”Cueva Alfredo Jahn” Venezuela, Atti 17th Congresso Nazionale di Speleologia, Castelnuovo Garfagnana 1: 155-159
First description of non-cave occurrence: Shannon E.V. 1927. Ammoniojarosite, a new mineral of the jarosite group of Utah. American Mineralogist 12: 424-426
Longitude: 66°16'21''W
Length: 4290
Water: temporary flooding (in the tropical rainy season)
Type of rock: limestone
Cave temperature (°C): 22-26
Group: Sulfates
Chemical formula: (NH4)Fe3+3(SO4)2(OH)6
[According to the official IMA-CNMNC List of Mineral Names (http://nrmima.nrm.se/imalist.htm)]
Deposition and stability: by evaporation in the dry season (water moves by capilarity up the cave walls) N, Fe and SO4 are supplied by a large amount of organic matter carried into the cave by the river, from the outside tropical forest
+ hydroxylapatite
- Trigonal