Doctoral Dissertations


"The important and highly productive Florida land-pebble phosphate field is located in west central peninsular Florida in portions of Hillsborough, Polk, Hardee, and Manatee counties. The Pine Level phosphate area, described in detail in this report, is south of the previously known and mined deposits and occurs in portions of Manatee, Sarasota, and De Soto counties. Results of the current geologic study of the Pine Level phosphate deposit and the evaluation of the overall potential of this southern part of the land-pebble field are presented.

The entire southern part of the phosphate field is underlain by more than 15,000 feet of Cretaceous and Tertiary carbonate strata. Phosphate deposits are confined to a thin clastic veneer of sediments that overlie the carbonate strata, and include the upper clastic member of the Hawthorn Formation of Miocene age, the Bone Valley Formation of Pliocene age, and unnamed strata of Pleistocene age. The total thickness of the phosphatic veneer is somewhat more than 100 feet.

The Pine Level phosphate deposit, characteristic of the heretofore undescribed phosphate deposits in the southern part of the Florida land-pebble phosphate field, is compared with the deposits of the main producing area in the northern part of the field. The Pine Level deposit differs markedly from the deposits in the main producing district. The differences include the more localized and erratic distribution of mineable phosphate concentrations, inclusion of portions of the upper clastic member of the Hawthorn Formation within the mineable unit, origin and age or the deposits, significant contrasts in pebble and concentrate quality and quantity related to the mode of origin, the lack of development of the aluminum phosphate zone, and the enrichment of the contained carbonate fluorapatite by replacement processes.

Very gentle scarps, representing Pleistocene sea standstills, divide the land-pebble field into several physiographic subdivisions. The physiographic provinces of the land-pebble field and the origin of the Pine Level deposit are related to three, and possibly four, Pleistocene interglacial marine advances that have reworked and recycled the apatite particles of the Bone Valley and Hawthorn Formations into new lower-level Pleistocene deposits that surround and flank buried remnant paleo-islands of the Bone Valley Formation.

Field relations, chemical analyses and petrographic studies of a series of apatite pebbles ranging from deeply buried, low-grade, black, impure apatite to shallow, high-grade, relatively pure, white apatite, indicates that high-grade white apatite in the Pine Level deposit is derived from initial low-grade black apatite. The alteration occurs by progressive replacement of mineral impurities within the black apatite as erosion continually reduces the depth of burial and the black apatite is subjected to increasingly acidic and oxidizing ground water activity.

Simplified evaluation criteria that serve to identify economically valuable deposits of the Pine Level phosphate type are described. These criteria are easily and readily determinable by the exploration geologist or engineer in search or such deposits.

The slimes (clay) content of the Pine Level phosphate deposit is much lower than in the deposits of the main producing area and provides the basis for a new method of land reclamation that may eliminate the expensive and difficult conventional method or slimes disposal in permanent storage reservoirs"--Abstract, pages ii-iii.


Proctor, Paul Dean, 1918-1999

Committee Member(s)

Spreng, Alfred C., 1923-2012
Grant, S. Kerry
Christiansen, Carl R., 1921-1997
Bolter, Ernst


Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Geology


University of Missouri--Rolla

Publication Date



xii, 182 pages

Note about bibliography

Includes bibliographical references (pages 140-144).


© 1972 Dean Stanley Clark, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Phosphate rock -- Florida
Phosphate minerals -- Florida
Geology, Stratigraphic

Thesis Number

T 2779

Print OCLC #


Electronic OCLC #


Included in

Geology Commons


Dissertation Location