THE PHOSPHATE ROCK DISCOVERY.

Otago Daily Times, Issue 12403, 12 July 1902, Page 2

THE PHOSPHATE ROCK DISCOVERY.

■ Br PROFESSOR .IAMES PARK, F.fi.S., Directok Ota go Univkroitv School of Minna. Tho discovery of pliospliatc rock was made some 15 mouths ago by Mr Ralph A. Ewillg on what is now a portion of (he Horseshoe ostatc, at a point about a mile west of Clarendon railway station. Subsequent, search has shown that phosphatlc rock exists in many places on the estate, winch embraces altogether an area of two square miles, including, among othor points of interest.. the well-known lime quarries at Milburn; PHYSICAL FEATURES. From the low-lying valley at the south end of \\aihola Lake, along which tho Dunedin-lnvercargill railway runs to Milton, tho land rises to the westward by a succession of low, gentle, undulating hills, from which, by a long, easy slope, is reached the summit of the semicircular ridge whose contour probably., suggested, the. oresent . name of the estate. The point of the' horseshoe is directed toward Milton, with the Milburn quarries on the outer rim, and Horseshoe Bush on the inner. The summit of the ridge is fairly flat. Tho descent into the bend lslong and easy, but on the Milburn side it is generally abrupt, and in nntny places quito precipitous. The surface is open agricultural land, much of whioh is at present under cultivation. GENERAL GEOLOGICAL FEATURES. The general geological structure of the district is very well seen in the section lrom Uaxendon westward across the Horseshoe estate in a distance of perhaps a mile mid a-half from the railway line. After leaving the flat, the low hills fu--t crossed are composed of mica-sehist of probably Silurian age, lying nearly horizontal Proceeding westward, the schist is overlain % the lower Eocene quartz grits and conglomerates which usually form the lowest member of the.coal measures in Southern Otago The grits are in turn followed conformably by glauconitic greensands, limestones, often glauconitic, and a soft, brown candstono. The lattc-r is overlain by a (low of basalt which caps the horseshoe ridee referred to above. 8 The series of beds associated with the . limestone lies nearly horizontal in the Horseshoe Bend, but rises gently to the south-west, the inclination for the most part Iwing so gradual as to be perceptible only by- comparing the altitudes of the limeetone outorops over wide intervals. The phosphate-rock, to be more particularly described hereafter, occurs in pockets in the limestone, and is covered in most places with an overbnrden of brown-coloured sands. A .study of the topographical features of this- -area, when considered in connection with, the disposition of the rock formation shows that the present contours were determined by denudation long after the eruption of the basalt cap,. •• CLASSIFICATION OP ROOK ' • FORMATIONS. ' For purposes of description and correlation the rock formations present in this district may be classified, according to their respective ages, as follows, excluding the recent alluvia, of the flats and swamps: — Post-Miocene—Basalt flow. Upper Eocene—Brown sandstone. I/owfer Eocene—(a) Limestone: 1, Upper horizon; 2, lower horizon, (b) Glauconitic eandstone. (c) Quartz grits ar.d conglomerates. Silurian—Mica-scliisL 1 Silurian. f .' The mica-schist crops out behind Cemetery Hill, about 45ft above the surface of AVaihola Lake. It forms tho basement rock of this and surrounding districts, cropping out along tho western boundary of the HorseshoQ. estate, whence it extends westward and' northward" throughout Central Otago. Near the cemetery, and all around, the echist lies in a nearly horizontal position, but it would not be safe from this to conelude that It had occupied, this position from the time of its formation until now. A rock of such antiquity must, of necessity have* been subjected to all the stresses and foldings which have affeoted the younger formations in this region; and it is only reasonconclude that the direction of tha later'secular movements has been to flatten strata that were previously highly inclined. Lower Eocene. (c) Quartz Grits and Conglomerates.— These ride hard on the mica-schist, from which the contained quartz grains and pebbles wore derived. Here, as elsewhere throughout Southern Otago, the cementing medium of the grits is brown peroxide of iron, and here also these beds possess their usual flaggy structure. Where the iron peroxide occurs in large excess it presents a fine mammilaiy structure, inerusted on tho flat surface of the grit-stone. These quartz, grits, generally known as coal-grits, from their close association with the brown coals of Otago, in most places Contain traces' of gold originally derived from- the. schists from .which they were formed. And although the grits themselves have seldom or never been found sufficiently rich to be worked directly for their gold contents, it is, nevertheless, of importance to mention that much of the alluvial gold of Otago has been derived from a rewash of the grits in which the gold ban beeu collected in a more concentrated form. ' '■ The area occupied by the grits is much obscured by surface earths and large boulders of basalt, which render it impossible to measure the thickness of these "beds or ever determine whether the fireclays and brown coal which usually accompany them are present hore or not. (h), Glauconitic Sandstone.— I This rock is well exposed at the pliospliatc quarry workings at Kiln Point, opposite Clarendon, and at Milburn quarry. The section at the former place is obscured with slope deposits, and in consequence the thickness of the sandstone could not be determined accurately, but it is probably not less than 40ft or 50ft. At Milburn a thickness of 40ft is visible below the limestone, and there, also the base of the section is not seen. The sandstone is generally coarse in texture, and, except where it is highly calcareous, never shows any planes of stratification. It contains a considerable propor- j tior, of glauconite, the hydrous silicate" of ] iron and aluminn to which tho rock owes its greenish colour. ( At Kiln. Point this sandstone was found to contain a few specics of marine mollusca i mostly broken and fragmentary. Of theso i were collected a large smooth peeten, pro- ■ balily Pccten hochstctteri, a small peeten ' with large distinct ribs, probably P. William- i soni, and Serpula. In addition to these, Mr i R. A. Ewing found a very large shark's i tooth. ■ At Milburn were found Peeten hochstet- < ten, a fragment of a large, strongly ribbed i l'ecten, or Lima, Serpula (2 so.), Balanus, i and a species of small oyster. i These forms are all characteristic of shal- < low water conditions, and show that the i sediments forming this sandstone accunui- : lated near tho shore-line of a shallow sea, ] with shoals of rock and stretches of' clcar sand. Oil the other hand, the mineral glauconite is known to lie formed by filling or replacing organic bodies, generally foraminifera, by a process of slow replacement, molecule by molecule, under conditions which would require the absence of strong sea currents, and a coast-line free from the encroachment of fluviatile deposits. (a) Limestone.—This rock has its greatest development at Milburn quarry, where there is a face exposed showing a thickness of "bout 65ft. The total thickness from the highest pinnacle down to the upper surface of the , glauconitic sandstone is probably SOft. ' At the phosphate quarry at Kiln Point only the lower horizon of the limestone is exposed; while at Milburn both the lower and upper horizons are seen. The lower horizon comprising, perhaps, a thickness of 25ft. is speckleil with eflaueonitc, and, being sandy or arenaceous, forms an inferior limeStone. The upper horizon is dull grey in colour, almost free from glauconite and of purer quality than the bai-e. Tt is often flaky qnd splintery, and. being fine grained 1 and earthy in some places, bears a stroll" j superficial resemblance to the Amuri lime" 1 stone of Northern Canterbury, with which, however, it has no connection. In the spoil heap of the qua Try at Mil- ' hum were found the jaw and teeth of a 1 Zugledont. whale, Peeten hochstctteri, 1 Meoma orawfordi, a Waldhemia, and a ' branching net coral. '■ This rock is the horizontal or time cquiva- 1 lent of the Oamaru stone, which if the clos- ' ing member of the New Zealand coal-bearing series of rocks. It is the most characteristic and persistent member of that series, and is seldom or never absent where coal is found' Jt occurs throughout both islands, and is everywhere easily distinguished. T n places, through the scarcity of lime, it. is little more

than a calcareous sandstono or impure lime V stone; while in other places it is very pun and highly crystalline'in structure. In different districts,it has received tin name of the locality in which it is found ! t Thus, in Southland, it is called the Wintoi limestone; in Bruce County, the Milton oi Milburn limestone; in North Otago, Oamaru stone; in South Canterbury, the 1S Waihao limestone; in North Canterbury, L Weka Pass stone; at Mokaii, Moltau lime- " stone, in the King Country, Te Kuiti lime ' stone, at Raglan, Raglan, limestone; in lo \\ aikato, Taupiri limestone; and at Whanp. garci, ITikurangi, Kawakawa, Waipu, it lc has received these names respectively; .and , s " in many other localities which need "• not be specified it has designated by a local 0 name. Is This limestone is very variable in physical ■s character and composition. Even in the same horizontal plane it may be seen to pass gradually and insensibly from a compact limestone into a calcareous sandstone, h often within a distaiicc 'of'• half u mile oi' 0 IP??. |. liionn Saiulsloiie.—From . the. upper stira face of the limestone to the basalt can s there is an interval of 120 ft t« 150 ft in d vertical height, apparently occupied' by a e yet owish-hrowu sandstone, the cliaractor t and disposition of which could not bo asCer- .- tamed on account of it,, outcrop being e obscured bv a heavy slopo deposit of black [j earth mixed with stand. t In the Oamaru and Weka Pass districts, 0 wnere the sequence of lower Tertiary strata I- is very complete and characteristic, the u Oamaru a«d Woks, Pass calcareous sandstones which, as we have seen, are the time l( equivalents of the Milburn limestone, are . followed quite conformably by the Hutchison quarry, or Mount Brown beds, which consist of yellowish-brown calcareous sandstones containing a rich assemblage at u man lie forms. 1 Until something more definite is ascertained about the sandstone lying above the 3 limestone on the Horseshoe'estate, it may be correlated with the Hutchison quarry t horizon of upper Eocene age, The work soon to be undertaken by the . owner« of the estate to develop the phosi phate deposits will doubtless uncover many - interesting and instructive sections of this t rock. 1 _ Barai.t, • This occurs as a true floiv. It rests on the upper surface of the brown sandstone, 1 and caps all'the higher hills. As its junction with the underlying rock-is everywhere ■ obscured by slope deposit, its Ihieknets cannot be determined, but at the old cemetery ! quarry the depth of the flow cannot lie ! less than 100 ft. ' This basalt is excessively fine in texture, ' at most places possessing a clean, splintery ' fracture. In tha face of the cmnetery quarry it exhibiis a rudely columnar structure. Here also its weathered surfaces possess a deeply corroded appearance, and the usual splintery character is absent except in one narrow bond near the centre oT tho higher part, of the quarry face. In polarised light, thin slices of this rockShow ail abundant dull grey or seini-onaque clspathm base, with augite and' olivine, tie latter often serpsutmiscd. Idiomorphs iCis>pai' are absent. The base, however, is orowded with acicular mierolites, some of which appear to exhibit poiysynthetic twining. Magnetite is very abundant. In the absence of rocks overlviug the •basalt it is impossible to fix the" date of its eruption even approximately, fa |,; s work on the geology of Otago (187; i, p. 56), aiU | ! tCl r' considers the baFalt head of Waihola' Lake, with which this .lasalt lias probably some. association, to be contemporary with .his Oamaru forma' tion of lower Miocene age: but the evidence on which (his conclusion is based is not given. At Cemetery Hill the "flow rests on micaschist near Kiln Point on tho coal-grits and elsewhere on the HorFCshoe estate on the brown sandstone overlying the limestone. Ihis shows that the Eocene stnta were deposited, consolidated, elevated and denuded prior to the eruption of the basalt which may have taken place in - upper aliocene or Pliocene times. PHOSPHATE ROCK. This was first found at Discovery Point, at the head of the Rend, where it'resh on the upper surface of the limestone. Here itlornis a massive outcrop, from 12ft to 18ft high and from four to five chains Ion". Tt consists of a very dense gvey or yellowish grey phosphate-rock, very rich in calcium phosphate. la places it is nearly pure phospnonte, occurring in narrow-banded pale yellow and grey concretionary masses po'i sessing a, tendency to exfolite 'in layers when struck with a bammer. Cavities in this rocs wore found to -be inerusted with a mammilary structure, The extent of the deposit at this place has not yet been determined. , .Another outcrop of phosphate-rook crop? out on the side of the valley opposite Discovery Point, and near it several lareo masses of tins mineral occur in a small depression in the hill about 20ft above this outcrop. I'liese masses arc obviously not in Situ, and'appear to have fallen from a higher elevation, wluclii would lend to indicates two horizons of phosphate-rock between the limestone and basalt. At Kiln Point a considerable amount of stripping and trenching\lias been effectedand here much interesting information was obtained concerning the mode of occurrence ot the phosphate-rock. At this place the outcrop has been stripped tor a distance of nearly two chains, exposing a very clear vertical section of the phosphate and underlying limestone. Jhe phosphate varies from 3ft to 12ft in thickness, and rests in a series of pockets ill the limestone. In the face behind the old lime kiln tliero are three shallow pockets the most southerly being 45ft wide the second 18ft, and the third.about 22ft, varying ill depth from 2ft to 6ft. The pockets are separated from each othor by ridges ol limestone averaging 3ft or 4ft wide,'as shown m sectiwi I,

The phosphate fills the pockets and rises above the level of the dividing ridge of limestone, a height varying from 10ft to 3ft, i the greatest depth occurring at the north- i east end of the section. j The phosphate-rock exposed in the facc : of the open cutting is much broken nnd crushed, and sometimes shows slickensided surfaces. It is yellowish-brown in colour, I with irregular seams and patches of whitish- ' grey. The presence of sand renders it soft and friable, and of lower grade than that exposed at Discovery Point. j At tho most easterly point of the open ; cut masses of fairly pure phosphate-rock contain inclusions of basalt occurring in small angular or nodular fragmcpts, whic'u are seldom over 4in in diameter. In a deep, narrow trench above the open cutting the phosphate is mixed with • glauconitic greensands, which are. said to be highly j phosphatic (sec section II), '

The phosphate-rock has been exposed by a long trench some 12 chains north of Kiln Point, but uo feature of spccial interest is disclosed in this dircotion. At Milburn lime quarry the surface of the Eocene limestone presents the most marked irregularity. Under the influence of both chemical and physical erasiou it lias been formed into wide basins and dcop well-like holes, surmounted by. overhanging knobs and spires of limestone. The basins are filled with yellowish-brown sands, as shown in section 111.

e- On the right sido of tho present quarry io facc, the upper horizon of limestone has been eroded down to tho lower moro sandy lo and iflauconitic horizon, on tho irregular ■I. surface of which there rest two small patched of phosphate-rock, as shown in section IV. i ' r I

v On tho right bank of a small stream, neai >r Sutherland's limestone quarry, thero is r high face of phosphate-rock resting in ti liasin iii the lower horizon of limestone; p and a few hundred yards south-west of Milu burn quarry there is a similar, but smaller, a outcrop, which also appears to lie on the higher part of the lower horizon. The sur- '• face contours and tho prc«ence of basalt K fragments in tho phosphate-rock at Kiln K Point tend to indicate that the formation of tho deposits took clace in comparatively i> recent times-probably in the Post-Pliocene " period,—and obviously sinco tho present- eon--5 tours were determined. Hcnco the phosphate will be marginal, and follow e the line of limestone outcrop, contouring ° around tho slopes of the. hills bounding'tho | valleys and shallow basins. . . Origin- op Piiosphatk Rock. J Pliosplinte-rock consists of tri-ealcium phosphate, which has the formula Cn, 1\ O . - It is often_ called bono phosphate of liniei 3 because it is the subfltanee of which bone is r composed. r The bones ot all vertebrate animals content about 60 per cent, of tri-calcitim plios--3 phate., while the excrement of some is also - ricii in the same substance. I Although invertebrates rarely contain 5 phosphate of lime, (here are some notable exceptions—namely, the lirachiopods Lingula and Orbicnla: also Conularia, Kerpulit.es, and some rceent and fossil crustaceans. Hence deposits rich in phosphoric anhydride (I o O s ) aie found in rocks of all ages from t ' ,L \ Thiureiitiaii up to nearly the recent ponod. Tlie, format ion of phosphate is generally believed to have been due to the leaching or lixiviation of phosphate-bearing rack;? by water containing carbonic and other oiganic acids, followed by Ihe subsequent concentration of the phosphate under favourable conditions. In some eases tho phos-phate-bearing solutions entered limestone caverns and deposited their calcium pliospliatc there; and tho subsequent removal by solution of the walls of the caverns either wholly or partially, left the phosphate ill the remaining sands or clay! Tt -may be of some interest- to note that the apatite hods and veins of Ottawa, in Oansda, ooour in rooks of Lnnvpntian The brown phosphate roo!; of Tonnossee ban bnen derived from'flm weathering () f rnrtnin lihosphatic layers in 'the lower Silurism limestone which forms the basin of middle tcnnessce. These, layers do not occupy an unvarying strafigraphicnl position, but- occur ill various horizons m the lower Silurian." The phosphate deposits in t.lio South of i gland, in France, and Belgium occur associated with cretaceous chalk. Those of Algeria and Tunis are of T'>cene nge, th-> phosphates occurring in nodules in marl, ol as pho.-phntie limestone. In Algeria, which has been estimated bv M. Chateau,' a Trench miniiis routineer, to contain from 150.000.000 to 200.000.000 tons of phosphate rock, it is considered risky to mino rock under 60 per -cent, of the t-ri-calcic phosphate. f The celebrated phosphate deposits in T'enimailar Florida occur in detached pockets in the uneven surface? nf an I'lcecne lime- i flone, and in 'Western Plnrida on Miocene limestone, um'cr geological conditions which seem almost the same as those existing oil the Horseshoe estate at Clarendon. - The once-famous beds of South Carolina are considered to bo of Post-Plicene agc.t The phosphate or lime formerly worked at Arulra and Sombrero, in the West Indies, was oridnally a coral limestone converted into a phosphate by the percolation of water containing phosphoric acid'derived from bird-guano. The geological conditions which aceompnny and doubtless determine the presence of workable deposits of iihosnhate are the prcFcnee ov n pliosplmto-brnrinfr formation ut the surface, and a favourable no?ition for jsputhovinp; and eonc?ntr:>tion of Tihosphate by replacement or FProntiurr onriohmont.. To favour the formation of large deposits it is further liecp-siny that tho topographical conditions should be such as to .favour the weathering of the nhosiihatic beds over con.'■idcraWo areas. Should the phosphate-hear-ing bed. in- example, crap out on a steep p'ops, tho width of snrfaee where Ihfi woathorinp: can Inko* pli-re will be Hirily limited in extent, the greater part of the formation fccinr pimcofod by the superincumbent strata. Hence phosphiife deposits left by leaching, ov produced by coueentration on such steep slopes will be nf small extent and in a position easily removed by denudation, On the other hand, where the, phosphatebearing rock is exposed on long, gentle slopes, or over an extent of level country, well-drained by streams, the conditions will llC" favourable for the leaching of the roclc over correspondingly wide areas, and eon«enueritly favour the formation of lar*c deposits. ° So far as known to the author, Ihe discovery of workable deposits of phosphate of lime on the Horseshoe estate at Clarendon is the first in Australasia, and, apart from its importance to the owners, is "certain to

prove of inestimable value to the agricultural interests of the colony. | 'flic evidence available' from a surface j examination shows that n large quantity of j phosphate-rock exists in this district, but, until the deposits have been fully developed it would bo obviously impossible to express i the tonnage' numerically. j This discovery will doubtless be followed by other discoveries in different parls of the colony 111 districts where the same geoloI gical conditions exist, the most likely localii ties being in Southland, North and .South ' Otago, North and South Canterbury, Marlborough, Raglan, and North Auckland dis-Phosphate-rock is easily overlooked, as witness the doposils in Milburn quarry expjscd to the view of all passers for years. The purer phosphorite is often very com- , pact, fin© grained and hard, possessing also I the banded, wavy, and chalcedonic structure

| of chert or flinty quartz deposited from thermal waters, for which it was mistaken in the past at Milburn. The Calcareous sandstone or limestone overlying and forming the closing member of tho Now Zealand coal measures is found \ery widely in both the North nnd South * Willard Hayes. Animal Report U.S. Geological Survey Keports, 183S-99, p. 033, t Memoirs of the French Socicty of C.E., August, 11597. * Penrose—U.S. Geoi. Survey Bulletin, No. 46, 18SS, p, GO.

Islandr, as already indicated. ami whenever its mirfuco is weathered and uneven, flic material filling the irregularities, whether it lie hard rock or soft, sandy marks, should lie submitted to chemical examination for determination of phosphoric acid.

ir) To become of commercial value a phosa , phale deposit'should fulfil the following a requirements:— ' ;; | 1. Of such magnitude as to justify the !- , erection of tramways and ' other surface I', | plant necessary for development and in j winning. . . r * ' llg ' l S 11 "' 0 '. averaging ' ess than It l 50 per cent, of tri-calcic phosphate before n dressing. if | 3. In a position easy of access to a raily way or seaboard. 10 | f: ®". s y to win—that is, in a, position ill !- ; which it can 'be worked water-free by open 5. cuts and quarrying. The overburden must w also bo shallow and easily removed, When g it exceeds 20ft the cost of stripping ruiis 0 away with the profit. It is only in exceptional cases that it pays to mine phosphate by underground workings. At Ross Farm, in Pennsylvania, n during the year 1899, 2000 long tons were ~ j mined from a stratum 30ft thick, 4000 ft J long, and inclined at an agio of 60deg from is j the horizontal. The stratum was mined to | a depth of 300 ft below water level, and i- averaged about 50 per cent, of phosphate. Here the matrix consists of a yellow marl, o j very easily and cheaply broken. Tho producer.-;, however, do not anticipate to lie „ nli.e to compete iu . distant markets with 0 J. ,'. l ° 1 ' 01 ' B ra 'les of phosphate from South Carolina, Tennessee, and Florida, but look . for a remunerative local market § i. WIN'NINTO AND MARKET PREe .PARATfON. •« J The process of winning nhosphale-rook r comprises stripping the overburden, breaking, and hoisting. In Florida the over- ' burden is removed with ordinary scoops and B mules. In one instance a steam shovel is j employed, and in a few mines where higliwa,er ' s available hydranlicking fc witli giant nozzles is used successfully. In • river deposits and deposits, under water -, centrifugal ]iumps or dredges are used to J ■ lift the material on to the barges, Watching, or the separation of the mineral 1 from its matrix, is required for all classes , fit phosphate. For hard rock, is > necessary for all material over 2iti or°3in mi diameter. The crushed rock is washed in t inclined wooden boxes about 30ft long and 3ft to Gft wide, with one or two revolving shafts or " logs," on which are mounted a Number (if Msuies spirally arranged. From the washer the washed rock is discharged into the "rinser," which is ■ a cylinder constructed of perforated boiler plate, slot-punched sheet iron, or wire cloth. Ihe length of the cylinder varies from Bft to 20it or more, its diameter from 2ft to [ 4ft. and tho mesh from one-sixteenth of an . inch to 2in. • The rinser is frequently mounted on fric- , tion rollers and driven by toothed gearing, and in both these respects closely resembles the cylindrical drying or calcining furnaces Used extensively in the northern goldfields. . T} le quantity of water used in washing and ; rinsing varies from 400 to 1000 gallons per minute, according to tho nature of the ; material being treated, a clayey matrix requiring more water than a sandy phosphate. Tho water used in the rinser is supplied . under pressure, being applied both to tho interior and exterior. At the best-equipped mines the rinsed rock is conducted on to an inclined picking belt, which is a heavy rubber belt passing over rollers. The picking is performed by two to ten men, according to the quality of tho impurities present. From tho picking-belt, the phosphate is discharged into hoppers, whence it is transported in trucks to the drying kilns or cylinders. To facilitate the handling of the material the crusher,■ washer, rinser, picking-belt, atul kilns arc arranged in tendem,_ with | sufficient' fall between each machine to assist tho movement of the material by gravitation. The burning or drying of phosphale is effected either in the kiln or in mechanical dryers,. tho ' former method . being generally employed for ■ hard rock phosphate. V'ood is. the fuel used, the wood and rock being laid in alternating layers at the bottom. The sides and ends of the pile are carried upward vertically by means of additional wood. From 1000 to 5000 tons of rock are burned in a pile, the neriod of burning extending over two or three weeks. On an average seven or eight cords of wood are used to burn ,100 tons. Eock piles are protected from the weather by sheds, since tho product, onee burned, must 'not be allowed to-get wet. From tho dryer the burned rock is conveyed in bucket conveyors to the storage bins to await transport to the market or manure works. STATISTICS.' The latest _ and most complete official statistics relating to the phosphate industry are those supplied by the U.S. (icol. Survey "i the annual report for 1899-1900, from which it is gathered that-.thc total production of phosphate-rock reported to the Surv*s'in 1f99 was 1,515,70?, long tons, valued at 5,084,0TGd01, equal to about 14s per ton distributed as follows:— 1 F10rida—726,420 tons; value 2,804,061dn1. bouth Carolina—3s6,6so tons; value 1,078,099d01. . ■ '

Tennessee—430,192: value 1,192.91Gd01. North Carolina—44o tons; valuo ||. 1 ennsylvanin--2000 tons; value 9000dol. L ah ' 3 included in that of South Carolina, i hosphato-rook mining in Florida lias been developed within the last 12 year*, the first production of 3000 tons of rich rock liavintr been made in 18S8. The noxt two year' were devoted largely to speculation and development, leading naturally to a " boom " 111 phosphates. Fancy prices were asked and given foi{ any land that showed indications of phosphate-rock, without regard to (he-grade of Ihe mineral.' • Mnnrnvliilp production increased, and in J leaehed 46,j01 tons; in 1892, ?.ijT,343 f uT/iinMQ eo .7?' ondin ß | y sle «dy r U|) I I 1b99. At the present time all rock t is sold on its chemical analysis, The Flo--1 rida phosphates yield about' 26 to 37 nev s cent, of phoiphorio anhydride, correspond--1 plfale" "6 80 1161 Colli ' t, ''" cn ' cie l''loß- - ! Ji'° WOrld ' S l ,rQl,M tio» of phosphates in - 1E96 was as under:-— • T ,^" ci ' in - 165 - 738 tQ ns; value, 500,905dol; Ii Belgium, 297.470 tons • value, 537,320d01: " S^K 517 ton . s; Vill «o.''P«0ilol; France, 3,< ■ 10116; vnluo > 3,502,027d01; Norway, , 2026 tons; value, 36,720d01; RussiaH: f Spain, ,770 tons; value, 2080dol; United . Kingdom, 3048 tons; value,- 26,250d01; • United States, 952,370 tons; value, 3 2,812,116d01. ' D " A serious competitor of the natural phosphates is fchd plioaphalie basic slag protlucod by tho Thomas steel process, especially in Continental linrouc. . In 1896 I'jiiropo produced 1,525,000 'short' tons of basic slag, equivalent to 800,000 tons of high grade phosphate rock,! of which Germany consumed 800,000 ton*. DESCRIPTION OF SECTIONS. Section I. Iviln Point—Face exnosed iielurul old kiln, (a) 'Phosphate rock, (r) Limestone. Section II —Kiln Point. (a) Phosnliatie Rrceiisiuulf?. (n) Phosphate rock. (c) Limestone. (t)} (Uaueonilic greeneands. section lll.—Milburn Quarry, showing surlaco of limestone in present working face. (.A) Brown sands. (n\ Limestone. Section iy, Milburn Quarry, showing Iwo patenes of phosphate rock resting on lower horizon of limestone. j S Twcniy-Gvsl Annual liiport U.S. Cieol | Survey, 1893-1900, p. 491. V Statistics not yet issued. ■