Rock Phosphate.

Kawhia Settler and Raglan Advertiser, 14 April 1905, Page 2

Rock Phosphate.

In the annual report of the Government Chemical Department, just issued by Mr B. C. Astor, F.C.S., appears the following, which wo have been asked to publish for the benefit of our readers :

“ The discovery of large deposits of this important fertiliser iu the southern portion of the colony has naturally stimulated farmers and others to send in samples of rocks which in any way resemble phosphate rock in order that it might be tested. “ Phosphrte r> ck owes its value te tho phosph ito of lime (trioalcic phosphate) which it contains, and which is the fertilising constituent that the Foils of this colony most need. To convert ruck phosphate into a marketable article it is quarried, graded, calcined in kilns, and subsequently ground to a fine powder. It is then ready for tbr- market. Tt may. however, be u'uiyeried iiite by tlie acti <n uf .-uslpliuric acid, tir.istiu mixed tertiliz.ee by the admixture of nitrogenous or potassium compounds, by either of which processes its value as a plant food is considerably enhanced. “ To assist those who are searching for this valuable mineral, a description of it is given, together with a few simple teste which may be applied in the field. “ New Zealand phosphate, hitherto found in the colony in workable quantities only in. Milburn and Clarendon (Otago), has a dirty-yellowish, white or light grey colour. Lt is easily distinguished from limestone, which it resembles, in not effervescing when brought into contact with a drop of dilute pydrochloric, sulphuric or nitric acid. It is harder and heavier than limestone, and has no trace of crystalline structure. It is with diftrcnlfy stjratebefl with a knife-blade, but it L potter than :cbt«ipar and than most silicate socks liable to bu mistaken for phosphate and which a blade-knife will not scratch, dome phosphates have a tendency te exfoliate, or shed their fragments in layers, when struck with a hammer. Phosphate rock should be looked for in all limestone districts. The deposit at Clarendon rests directly on limestone. A limited number of specimens of New Zealand phosphate rock are available for distribution to farmers, prospectors, and others interested, and will be sent free on application. If, therefore, a rock is found which is—(1) Dirty - white, yellowish, or greyish white in o jlour ; (2) Softer than quartz and feldspar, but harder than limestone; (3) Heavier than limestone . and quartz ; (4) Non 1 crystalline : (5) D -m t off i’Y? fr with ttCftd—A specimen in the iirj. ii.stance should be sent by pojt io die DepaivOjeut’s chemical laboratory for analysis. The sample will bo tested and reported on free of charge. “ The samples, eta., should bo sent to—The Chief Chemist, Department of Agriculture; Wellington.”