Clear Springs Mine, Florida - Bone Valley locality famed for gemmy blue-green vivianite crystals on carbonate-phosphate matrix, prized by collectors.
Key facts
Clear Springs Mine is one of the most specimen-significant stops in Florida’s Bone Valley: not because it produced a large variety of cabinet minerals, but because it yielded some of the best-known vivianite from the central Florida phosphate district. The mine lay at Homeland, near Bartow, Polk County, in the land-pebble phosphate belt where Miocene to Pliocene phosphatic sediments of the Hawthorn Group–Peace River Formation/Bone Valley interval were stripped in broad, dewatered open pits. In the ore zone the commercial phosphate was chiefly carbonate-rich fluorapatite—francolite—mixed with quartz sand, clay, dolomite, phosphatic rubble, iron oxides, sulfides, and a surprisingly rich suite of secondary phosphates.
Collectors remember Clear Springs for gemmy, lustrous, blue-green to blue-violet vivianite crystals on pale carbonate-phosphate matrix. The best specimens are not large by Bolivian or Cameroonian standards, but they have a distinctive elegance: sharp single crystals, sometimes doubly terminated, sitting isolated on buff to cream-colored matrix, with the color contrast that makes a Florida phosphate vivianite instantly recognizable. Published specimen references include crystals from only a few millimeters to about 3 cm, with 1–2 cm pieces already desirable when well terminated and undamaged.
Regional View
Country View
Geologically, Clear Springs was valued by field-trip leaders because it exposed an unusually complete phosphate section and an intensely altered upper ore zone. The upper part of the section shows the leached and supergene-modified nature of the Bone Valley deposits: clayey sand with phosphatized crusts, abundant fine francolite, and lower gray-green sandy clay matrix packed with black phosphate pellets above phosphate-bearing dolomite. That weathering profile is the reason the mine is more than an industrial phosphate locality—it is a natural laboratory for the secondary iron and aluminum phosphate assemblages that fascinate micromounters and systematic collectors.
Photo: Wikimedia Commons
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Clear Springs Mine was an open-pit land-pebble phosphate mine at Homeland, just south of Bartow, in Polk County, Florida. The mine belongs to the Central Florida Phosphate Mining District, the historic Bone Valley district, where phosphate mining moved through shallow, laterally variable beds of quartz sand, clayey sand, sandy clay, phosphorite, and dolomitic bedrock. The mine’s recorded coordinates place it near 27° 51' 55" N, 81° 48' 50" W, and older descriptions locate Clear Springs near U.S. Highway 17 and State Road 655, about four miles south of Bartow.
The ore was the standard central Florida phosphate “matrix”: a mixture of phosphate pellets, granules, pebbles and phosphatized limestone with quartz sand tailings and clay slimes. At Clear Springs, a published USGS section in Sec. 11, T. 30 S., R. 25 E. shows a shallow Holocene organic sand cap, Pleistocene sand, then 15 to 30 feet of clayey sand with irregular bedding, phosphatized crusts, and abundant white to cream clay-size francolite. Beneath that was the mineable matrix, about 30 to 38 feet in the described section: gray-green bedded sandy clay with black phosphate pellets and a crust of secondary precipitated francolite. Hard yellow phosphate-bearing dolomite appeared below, followed by softer dolomitic clay with phosphate and quartz sand.
That stratigraphy matters for specimens. Vivianite at Clear Springs is not a primary ore mineral; it is a secondary hydrated iron phosphate that formed where ferrous iron, phosphate, water, and reducing conditions came together in the sedimentary ore and its associated clays/carbonates. Pyrite and marcasite provide plausible local iron sources, the phosphate matrix supplies abundant phosphorus, and the highly altered upper ore zone created the chemical setting for secondary phosphates such as vivianite, metavivianite, crandallite, wavellite, strengite, beraunite, cacoxenite, mitridatite, rockbridgeite, variscite, and related species.
Industrial mining followed the central Florida pattern. Overburden was stripped by draglines, the matrix was dug into slurry pits, broken down with water jets, and pumped by pipeline to a washer/beneficiation plant. The coarser pebble fraction and finer concentrate were recovered; quartz sand and clay slimes became waste streams. A 1982 Geological Society of America field-trip notice singled out Clear Springs as unusual because of the “extreme supergene alteration” in the upper ore zone and noted that the Page 747 dragline working there had a 72 cubic-yard bucket, then described as the largest in the field.
Ownership and operating history pass through the major corporate names of the district. Mindat records the mine as owned by International Minerals & Chemicals Corp.; later environmental and facility records use IMC-Agrico, IMC Phosphates, Mosaic Fertilizer, Mosaic Phosphates, and Clear Springs Land Development Co. in connection with the Clear Springs/Noralyn/Phosphoria area. USGS water-quality and hydrogeologic data were collected in 1979–1980 at an International Minerals and Chemical Corporation Clear Springs mine waste-disposal pond near Bartow, and the mine was still a recognized field stop in 1983. EPA abandoned-mine documentation later listed IMC/Clear Springs Mine as a closed mine and beneficiation plant with clay settling areas and sand tailings. Florida reclamation reporting lists Clear Springs among shut-down phosphate mines with final reclamation complete.
Modern collecting access should be regarded as closed unless explicit written permission is obtained from the landowner/operator. This is private, reclaimed and environmentally managed phosphate land, not a public rockhounding site. The central Florida phosphate district as a whole has become far more restrictive than it was during the great years of mine collecting; active cuts, dragline areas, slurry pits, clay settling areas, and reclaimed mine land are hazardous and regulated. Any specimen entering the market today is far more likely to be old-stock material from mine employees, field-trip participants, micromounters, or long-dispersed Florida collections than a recent self-collected piece.
The notable specimen finds appear to have been small, selective occurrences rather than large commercial pockets. Clear Springs vivianites are represented in museum and private collections, and at least one Canadian Museum of Nature specimen photographed by Jeff Scovil is recorded as a 1.9 cm crystal. A widely reproduced Rob Lavinsky specimen is 1.8 x 1.6 x 1.1 cm overall, with a 1.1 cm doubly terminated, gemmy, bicolored crystal on matrix. Mineralogical Record indexing notes 3 cm euhedral Clear Springs vivianite, which marks the upper end of the published size range for fine crystals from the locality.
Vivianite is the signature collector mineral of Clear Springs Mine: sharp, lustrous, transparent to translucent crystals in blue-green, sea-green, dark blue, and violet-purple tones, typically on pale carbonate-phosphate matrix rather than as loose mud-stained fragments. Published and photographed pieces document crystals from about 4 mm through the 1–2 cm range, with indexed references to 3 cm euhedral crystals; the best examples are isolated, complete, terminated or doubly terminated crystals with bright luster, strong color zoning, and minimal edge bruising. Fluorapatite/carbonate-rich fluorapatite is the most important matrix association, with the broader altered phosphate assemblage including iron phosphates, clay minerals, pyrite, marcasite, and iron oxides. Ordinary Clear Springs vivianite is small, dark, incomplete, or partly embedded; the prize pieces are those that keep the Florida look—gemmy blue-green to violet vivianite standing cleanly from pale phosphatic matrix.
Other documented Clear Springs minerals show how chemically busy the altered phosphate matrix was. The list includes carbonate-rich fluorapatite/francolite, crandallite, fluorwavellite, wavellite, strengite, variscite, beraunite, cacoxenite, mitridatite, rockbridgeite, phosphosiderite, millsite, cyrilovite, metavivianite, and ferrostrunzite, together with pyrite, marcasite, hematite, goethite, gibbsite, gypsum, jarosite, whewellite, siderite, dolomite, quartz/chalcedony, opal, kaolinite, and native sulfur. Clear Springs is not celebrated as a type locality for a valid IMA species; its importance lies instead in being one of the best-documented Florida phosphate localities for attractive vivianite and a broad secondary phosphate suite.
Clear Springs vivianite is a locality-sensitive material: labels matter. Specimens may appear as “Clear Spring Mine,” “Clear Springs Mine,” “Homeland,” “Bartow,” or simply “Bone Valley, Florida.” “Clear Spring Mine, Homeland, Polk County” is the Mindat locality form, while older labels and articles often use “Clear Springs Mine, Bartow.” The spelling difference is normal, but a label that collapses the locality to “Florida phosphate mine” or “Bone Valley” is materially less precise. Because several central Florida phosphate mines produced secondary phosphates, locality discipline is essential.
The most common condition problems are those expected of vivianite: softness, perfect-to-good cleavage, edge bruising, dulling, and darkening. Vivianite is very soft and fragile, and Clear Springs crystals are often thin enough that even a small rub on an edge is obvious under magnification. Avoid water cleaning unless you know the matrix will tolerate it; pale phosphate-carbonate matrix can be friable, and old glued mounts are not unusual on micromount-sized pieces. Keep specimens out of strong light. Vivianite can darken as Fe2+ oxidizes toward Fe3+, and old specimens that were once brighter may now appear nearly black except on thin edges or with transmitted light.
Known modern fakes specific to Clear Springs are not well documented, but mislabelling is a real risk. Blue-green vivianite from Bolivia, Cameroon, Germany, Idaho, or other classic occurrences can look far more robust or dramatically larger than typical Clear Springs material. A convincing Clear Springs piece should fit the locality style: small, sharp, tabular to prismatic crystal or crystals on pale phosphatic carbonate matrix, commonly thumbnail or small miniature scale. Loose crystals without an old label deserve skepticism unless accompanied by strong provenance.
Market availability is limited but not hopeless. Clear Springs vivianite circulated through American collections in the late twentieth century, and old-stock pieces still surface. Fine matrix specimens with a complete, gemmy, well-terminated crystal above 1 cm are significantly scarcer than small dark crystals or micromounts. Anything approaching the 2–3 cm range, especially if euhedral and undamaged, should be treated as an important locality specimen rather than a routine vivianite.
On March 16, 1983, Clear Springs was the first stop on a Geological Society of America central Florida phosphate field trip led by Ralph Hall. The itinerary reads like a snapshot of a vanished mining district: a chartered bus leaving Tampa International Airport at 0830 hours, the Clear Springs Mine of I.M.C. south of Bartow, an ore section exceptional enough to be advertised in advance, and then the biggest dragline in the field. The Page 747 machine at Clear Springs carried a 72 cubic-yard bucket—an almost theatrical scale for anyone used to hand collecting mineral pockets. After the mine visit, the group was to go to Gardinier’s picnic grounds on the Peace River near Fort Meade for a pork-rib barbecue, then on to another mining cut to compare upper Bone Valley material with lower Hawthorn ore matrix.
Clear Springs also sits inside the larger Bone Valley fossil story, where phosphate mining opened the only practical windows into beds with no natural outcrops. The Florida Museum’s account of the Palmetto Fauna lists Clear Springs among the mines that produced early Pliocene vertebrate fossils. In the old system, many fossils were found by mine workers or geologists and accumulated in mine offices; visiting paleontologists acquired them by asking for donations. Later, beginning with S. David Webb’s arrival at the Florida State Museum in 1964, fieldwork became more stratigraphically disciplined. Collectors walked spoil piles and dragline exposures looking for exposed teeth and bones, while active cuts remained dangerous places where a single find could preserve sharks, rays, birds, horses, turtles, and terrestrial mammals in the same broader phosphate landscape.
That juxtaposition—industrial draglines, fossil bones, phosphate pellets, and delicate blue vivianite crystals—is what makes Clear Springs memorable. A specimen from this mine is not just a Florida vivianite; it is a small mineralogical by-product of a region where commercial fertilizer, vertebrate paleontology, sedimentary geochemistry, and systematic collecting all intersected.
