ASSOCIATED MINERALS AT THE THAMES.

Thames Guardian and Mining Record, Volume I, Issue 60, 15 December 1871, Page 3

ASSOCIATED MINERALS AT THE THAMES.

(BY MR. SKEY, GOVERNMENT ANALYST.) The minerals usually associated with the gold of this district, are pyrites, sometimes cupreous, and sequioxide of iron ; indeed, iron in some form or other is a constant asssociate—in the lower, or more compact strata, as the sulphide ; in the upper and more open parts, as the oxide, or sulphate with more or less pyrites. Along the walls of the old drives, the conversion of the pyrites originally present in the rock, to the oxide and protosulphate of iron, is at times complete for some distance in the wall. In some of the claims along the upper and middle portions of Tararu Creek, manganese oxides occur along with the gold to the almost entire exclusion of iron compounds.

In others, but these are comparatively few, sulphide of antimony with the various products of its metamorphis, is largely associated with the gold, this is particularly the case at the claim of the Criterion Company. Heavy spar (sulphate of baryta), Witherite (carbonate of baryta), Black-jack (sulphide of zinc), Calamine (carbonate of zinc), Diallogite (carbonate of manganese), Galena (argentiferous), occur less frequently. Crystallised silica (rock crystal) and ealespar among the non-metallic minerals, are both very generally diffused. A statement of the results of the examination of the more interesting of the Thames specimens received or collected, is here annexed. No. 870. —From the Silver Crown claim. Presented by Mr MacLaren, for examination as a silver ore. An excellent specimen of zinc blende (sulphate of zinc) ; is is well crystalized, and both the yellow and black varieties are exhibited. Associated with this ore, is a little argentiferous galena and copper pyrites; the matrix is quartz. No. 874.—Diallogite (carbonate of manganese), with calamine (carbonate of zinc). From a claim, high up on the Tararu Creek. Presented by the manager of Russell’s battery. The diallogite of this specimen contains a portion of carbonate of lime, but the amount of this has not been ascertained yet; it is coloied with oxide of manganese, and crystallized in large rhombohedrons. The carbonate of zinc forms lustrous colourless transparent crystals, attached to the former, but always external; these are well shaped, but comparatively small; they are interspersed, somewhat rarely, with small rock crystals. No. 902. —Galena. Long Drive claim. Obtained by Mr D. Monro. Examined especially for silver (by request) ; yielded only traces of this metal; in all probability the whole of the silver exists as a sulphide, in combination with the lead ore, since all galenas contain more or less silver. No. 875. —Manganite (hydrous sesquioxide of manganese). Tararu Creek. Occurs in a small columnar crystals, lining a cavity in an earthy-looking quartz rock. It was presented by the manager of Russell’s battery.

. No. 881. —Copper Pyrites. Golden Crown claim. Occurs in a small abruptlyterminating veins, in a drive recently made in this claim. It contains nearly 9 per cent, of copper. No. ,900 —Stibnite (sulphuret of antimony)! Criterion claim. A large block of quartz upon two faces of which nests of Stibnite crop out in large radiating crystals. This mineral is also interspersed throughout, but very irregularly, and generally in isolated crystals. The yellow stains appearing upon portions of the quartz and stibnite, is due to the presence of Cervanite (oxide of antimony), while the red substance forming small patches in the above (the cervanite), is Kermesite, or the oxy-sulphide of the same metal. In and upon the less antimonial portions of the specimen, numerous small colourless rliomboidal crystals occur ; these consist of heavy spar of baryta.) The whole of the specimen is thickly impregnated with small cubic crystals of iron pyrites (mundic of the digger), which is auriferous. The antimony ore has been specially tested for silver, by the wet process, the results being strictly negative. A great quantity of the quartz from this claim is more or less antimonial, to which circumstance the manager, very properly, ascribes the cause of much of the loss he experiences in milling it. No. 906.—Tufaceous Rock. Hape Creek. This stone outcrops about one mile up the creek, forming a bold bluff close to the tramway it has been used for the formamation of a resevoir at Goodall’s battery,

and as itißin contemplation"to extend its use for the general purposes of a building stone, an opinion was requested by Mr Simpson, the Provincial Assistant Engineer, as to its probable durability when so applied. It is a moderately hard coherent greyish slate-colored rock, of granular and massive structure, and homogeneous for considerable distances. It: is easy to work and dress, and can be quarried in large masses if desired. In one form or other it is a very common rock, but it occurs at this particular place in position and quality rarely combined ; there is, however, a stone cropping out at the next point above this, very similar, but sensibly harder, and in its mineralogical character partaking of an agglomerate. In their chemical composition both these stones no doubt compare with No. 461; they are certainly complexly constituted rock, prone to chemical change, but whether such change would have an indurating or disintegrating effect upon it, can scarcely be determined otherwise than by actual observations. It is proper to state in respect to this, that there were on view several roughly squared blocks, which had been lying at this quarry for six months, and the angles so exposed seemed quite sharp and well defined, whilst the stone itself appeared slightly harder than that recently quarried. No. 913. Manganese Ore (hydrous oxide). Tararu Creek. This was taken from the Yankee Doodle claim, by Mr Thorburn. It occurs very plentifully in a rich leader recently struck in this claim.

No. 914.—Crystallized Sulphate of iron. Long Drive claim. Uniformly occurring in all the old drives and workings of this claim, where the enclosing rock is or has been pyritous. It is this salt which, as before remarked, is I believe the, most actively concerned in the flowring of quicksilver. No. 923. —Native Lead. Presented by Mr Raithby. Obtained from the heavier matter of the wash of a creek; locality not stated. It is in pieces more or less rounded, some indeed quite spherical, and about the size of small shot, to which it bears much resemblance. I was assured, however, there was little possibility of it being anything of this sort, it being taken very soon after these diggings commenced. Lead, in its native state does sometimes, but very rarely, occur naturally ; when it does, it is generally in flattened buttons, but now and again in small spheres, a form which the attrition of fine sand around it would certainly have the tendency to produce. No. 929.—Chlorite. Tararu Creek. This occurs with more distinctive characters than usual in the damper crevices of the white tufa rock, some distance up this crock* No. 931.—Selenite (gypsum). Presented by Mr McDonald. A very fine, beautiful ciystallized specimen. This mineral is, as yet, larely found in largo crystallizations, though generally diffused among the calcareous and pyritous rocks of this district. No. 917.—Cavernous Quartz, with Rock Crystal and Dioptase (siliciate of copper). From the Wonder claim. It is in part irridesceut, from the presence of films of hematite upon its surfaces, which have varying degrees of thickness.