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Dunnellon Phosphate Company Plant One Historic 1906

Discovery of Phosphate in Florida

Some three decades after phosphate rock was first mined in England to be used in fertilizer, Dr. C. A. Simmons, who owned a rock quarry for building stone in Hawthorne, near Gainesville in Alachua County, had some of his rock sent to Washington, D.C. in 1880 for analysis. The rock was determined to contain phosphate.


Dr. Simmons launched the earliest attempt in Florida at mining and using phosphate in 1883. His attempts were short-lived, but by 1883 phosphate was also reported at other locations in Alachua, Clay, Duval, Gadsden and Wakulla counties.


Although Dr. Simmons is credited with the first discovery of phosphate in Florida, the Florida phosphate boom of the late 1800’s was triggered after the 1889 discovery of high-grade phosphate hard rock by Albertus Vogt near the new town of Dunnellon in Marion County. Mr. Vogt had noticed fossil remains of prehistoric animals in a nearby spring that reminded him of similar finds near phosphate deposits from years earlier when his family had lived in South Carolina, where phosphate was first found in the United States. Rock samples taken while sinking a well on his property were determined to have very high phosphate content. Vogt and a few other local citizens began buying up land in the area and the first hard rock production began in 1889 by the Marion Phosphate Company. This was followed by the Dunnellon Phosphate Company, in which Vogt had ownership interest, in 1890.

Florida Phosphate Mining History

Florida phosphate mining dates back to the first hard rock deposits found near Hawthorne in Alachua County in 1883. Endurance was imperative in the early years when phosphate mining was done with wheelbarrows, picks and shovels. Next came mule-drawn scrapers. Mechanized excavation began between 1900 and 1905 with steam shovels. Early steam shovels held only one cubic yard of earth, but one steam shovel operated by three men did the work 80 men did by hand.


Steam dredges and barges came into use in hard rock areas where the water level was too high for picks and shovels. Centrifugal pumps mounted on barges were also used to mine the river-pebble phosphate deposits in the Peace River until river-pebble mining ended in 1908.


Draglines, the current mining tool, came into use with the dawn of electricity and diesel power in the 1920s and 1930s. By 1930 these electrically driven draglines were adopted as the most economical way to mine land pebble. They also were put to use in the hard rock region.


The dragline significantly changed the mining operation. In 1900 it took a year to mine a 15-acre mine site with picks and shovels. Today one dragline mines 15 acres in a month.


Digging the phosphate out of the ground is only one step of the mining process. Phosphate comes out of the ground as part of a matrix, which is a mix of the phosphate, sand and clay. The phosphate must be separated from the sand and clay it has melded with in the ground over millions of years. Early separation methods included crushing, washing, screening and, in the case of hard rock, picking out silica by hand on a conveyor belt.


Separation advancements in the 1920s and 1930s allowed companies to begin salvaging phosphate particles they had been discarding as waste. Improvements were made in preparing matrix for washing and screening, finer screens were used, and equipment capacity increased. The most important change, however, was the 1927 development of flotation, which separates phosphate rock from sand based on their difference in hydrophobicity (water aversiveness).


Since 1942, most mining advancements have been in refining the dragline mining and flotation processes. Technology advances continue to make it possible for phosphate companies to mine and use lower quality rock. A research focus today (2005) is finding a feasible and economically attractive method for separating dolomite from the ore being mined. Much of today’s reserves are left in the ground because the dolomite, which contains magnesium, causes problems at the fertilizer processing plant.

Phosphate and How Florida Was Formed

Florida is blessed with a bountiful supply of phosphate that primeval seas deposited here millions of years ago. The phosphate comes from sediment that was deposited in layers on the sea floor. The phosphate rich sediments are believed to have formed from precipitation of phosphate from seawater along with the skeletons and waste products of creatures living in the seas.


In the early 1800s, it was learned that phosphorus promotes growth in plants and animals. At first, bones, which contain the element phosphorus, were used as an agricultural fertilizer. Today, phosphate rock provides fertilizer’s phosphorus.


Phosphate rock was first mined in England in 1847 for use as a fertilizer. It was in 1881 that Captain J. Francis LeBaron, of the Army Corps of Engineers, discovered Florida’s treasure in black phosphate pebbles in the Peace River. A “hard rock” phosphate reserve in North Central Florida was discovered next. Thus began Florida’s phosphate mining industry. Florida’s phosphate mining today accounts for about 80% of the phosphate used in the United States, as well as about 25% of the phosphate used around the world.

The Florida that we know today and the phosphate buried in its earth is a relatively recent product of geologic processes that have been at work for a long time.


In the 1960s, scientists introduced the theory of plate tectonics. This theory holds that the Earth’s crust is fractured into several large pieces called plates. These plates move around very slowly, propelled by powerful forces deep within the Earth. As the plates move, the continents are carried along on top of them as if they were passengers on a raft. Sometimes continents are split up – other times they are brought together. Throughout the long history of the Earth, this process has rearranged the continents many times.

Evidence from core samples obtained from deep wells drilled around the state indicates that the igneous and metamorphic rocks that Florida is built on may once have been part of Africa. These rocks became joined to North America more than 300 million years ago during the formation of the “super continent” that scientists call Pangaea. When Pangaea broke apart into the continents we know today, these deep “basement rocks” that underlie the state remained with North America.


Over the millions of years that followed, thousands of feet of sedimentary rock deposits accumulated on top of the underlying rocks to build up the land we see today. During this time, most of what is now Florida was underwater. Marine creatures in the form of coral, shells and skeletons deposited the limestone that makes up the sedimentary layers. As time passed, sea level dropped and the limestone became exposed as land.


Florida’s phosphate rock deposits are believed to have originated in several ways. Some of the phosphate may have formed when conditions in the seawater caused dissolved phosphorus to solidify, a process scientists call precipitation. As material settled to the bottom of the shallow coastal waters, it became part of the sedimentary layers that eventually formed the sediment that is mined today. It is also likely that excrement and sea life remains played a big part in forming the deposits. Bones, teeth, and other animal remains also contributed to the ore formation.


By about 12 million years ago, most of the coastline of Florida probably looked much like it does today in many coastal areas. In those times, however, the shoreline was located up to 60 miles further inland. In the shallow waters offshore a layer of clay and sandy limestone was deposited. Today this layer is known as the Hawthorn Formation.


Rivers and streams flowed down to the sea, carrying material washed from the land. This material was deposited in shallow lagoons and bays along the coast, forming deposits of sand and clay. These deposits contain the remains of land animals brought in by the rivers and streams, and also marine creatures that inhabited the coastal waters. These deposits are so rich in fossils, the term scientists use for evidence of ancient life, that they are known as the Bone Valley Formation. In Central Florida, the Bone Valley Formation is found on top of the Hawthorn Formation and is under about 20-40 feet of sand.

Fossils from the sedimentary deposits of the Bone Valley Formation are often uncovered in the process of phosphate mining and give us a glimpse of Florida’s prehistoric past. Bone Valley is the heart of Florida’s phosphate mining area.


Among the abundant fossils found in Florida are those from the sea creatures that lived in the shallow waters that covered Florida in the distant past. These fossils include the teeth of giant sharks and the bones of huge whales (both on display at the Mulberry Phosphate Museum). The remains of hundreds of species of land animals, birds, and plants are also found in the layers of rock beneath the present day surface. These fossils include many species that came to Florida to escape the advancing glaciers of the great Ice Ages. Some of these animals migrated to North America from other parts of the world. For example, some of these animals came across the Bering Strait land bridge from Asia when sea level was lower. Others traveled around the rim of the Gulf of Mexico, when areas that are now submerged were exposed.


Other evidence tells us that Florida supported this great variety of creatures with abundant food supplies made possible by a temperate climate. Fossilized remains dug from the Earth during phosphate mining tell us a great deal about the life of the past and about early geological developments in Florida.