66 THE MINERALS OF TASMANIA. 



111. DuNDASiTE ( 71 ydrated Carhono-phosphate of Lead 

 and Aluminium). 

 This new mineral compound forms an incrustation on 

 ferro-manganese gossan. It is composed of small spherical 

 aggregates, usually closely matted together. Under the 

 lens these bunches show an extremely fine radiating struc- 

 ture. The colour internally is silky milk-white, with a 

 velvety outer crust of a dusty yellow-brown. The surface 

 often has numerous adherent crystals of crocoisite, which 

 not rarely penetrate the mass. These crystals are always 

 minute, but remarkable for their extremely fine develop- 

 ment and acute angles. Its general habit of occurrence is 

 in somewhat small rounded aggregates, which show white 

 radiating tufts on separation. It is easily disintegrated into 

 fine silky fibres after the manner of chrysotile. In many 

 instances the individual tuft has as a nucleus a minute 

 crystal of the bright hyacinth-red coloured crocoisite, which 

 is again sometimes implanted on its surface. It often 

 occurs coating the interior of vughs in the harder gossan. 

 It is sometimes coated with a bright green film of extreme 

 tenuity ; this is probably a substance allied to pyromor- 

 phite. Again it is more rarely stained on the exterior 

 with a salt of copper to a pale bluish-green, and still more 

 rarely discoloured by brown hydrated iron oxide. 



The qualitative reactions of this new substance are as fol- 

 lows : ■ — In the matrass it becomes yellow and yields water. 

 It is infusible before the blowpipe, but on coal, with fluxes, 

 yields a considerable quantity of metallic lead, and coats 

 the surface with the characteristic yellow sublimate. When 

 moistened with sulphuric acid it gives distinct reaction for 

 phosphoric acid. In nitric acid it dissolves with strong 

 effervescence ; the residuum from the solution strongly 

 deflagrates and gives phosphoric reaction. The powdered 

 material, when moistened with cobalt nitrate, clearly shows 

 the beautiful blue colouration of alumina. With limewater 

 gives the turbidity of carbonic acid. Hardness about 2. 

 Locality : Adelaide Proprietary Mine, Dundas. 

 The following is a complete analysis of this new 

 species : — 



Pb = 38-84 per cent. 

 Fe =3-85 



Pormula for this species — 



Pb O X\, O32CO, 4H, 0. 



