Iowa · Dubuque County
Past Producer

Twin Springs Quarry

Dubuque County, Iowa, United States
Phosphorus-Phosphates
⌖ Show on mapUSGS source ↗
Commodities
PrimaryPhosphorus-Phosphates
Commodity typeN
Deposit
Deposit sizeS
Geology
Host rockSiltstone · Maquoketa Shale
Economic & production
Development statusPast Producer
Identification
Deposit ID10082055
MRDS IDW044564
RegionNA
Data scoreD
Coordinates42.52029, -90.84985
References
F1 < BROWN, C.E., 1966, PHOSPHATE DEPOSITS IN THE BASAL BEDS OF THE MAQUOQUETA SHALE NEAR DUBUQUE, IOWA, IN GEOLOGICAL SURVEY RESEARCH 1966: U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 550-B, P. B152-B158.F2 < BROWN, C. E., 1974, PHOSPHATIC ZONE IN THE LOWER PART OF THE MAQUOKETA SHALE IN NORTHEAST IOWA: U.S. GEOLOGICAL SURVEY JOURNAL OF RESEARCH, V. 2, NO. 2, P. 219-232.