Hardman and Hull — A Hitherto JJndescrihed Mineml. 16-5 



one way or the other in the present case, and I would prefer to con- 

 tent myself with calculating a formula on the supposition that that 

 mineral is only a silicate. However, the above analysis does not give 

 a reasonable formula in its entirety. Calculated as it stands, it gives 



M"3 M"'4 SisO^i + 7H2O, 



which fails to agree with any type of silicate I know of. 



If, however, we subtract one molecule of peroxide, and suppose it 

 to exist as a hydrate, and not combined, we get 



(M'3 M'V SieOie) + He M'^o^ + 4H,0, 



the first member of which is a condensed meta-silicate on the type 



H12 SisOis 



which would bring it sufficiently near the type of talcose and chloritic 

 minerals. However, the general constitution, even allowing for this, 

 is entirely different. Then again, we may suppose the excess of perox- 

 ide, as in the above, to act the part of an acid, an aluminate, or a 

 ferrate, which is not improbable, and we thus get a formula not unlike 

 that which has been proposed for ripidolite, but the silicate belonging 

 to a different condensed meta-silicic series, viz., 



[M"3 W\0, + W\-R, SieOis + 4H2O], 



a part of the water in this case being basic, as I have but little doubt 

 it is, acting in fact as a protoxide. 



It is extremely probable that the last formula gives a fair repre- 

 sentation of the molecular composition of this new mineral. 



I should wish to draw attention to one or two remarkable points 

 about this mineral. 1° the very large percentage of iron it contains, 

 and the small quantity of magnesia, although it is extremely refrac- 

 tory before the blow-pipe ; and 2° its very low specific gravity, not- 

 withstanding the quantity of iron it contains. The last circumstance 

 is, I think, due to the very large percentage of water. 



"With regard to its claims to be an original mineral, and not simply 

 a product of alteration, I would like to point out one or two strong 

 evidences. The mineral occurs coating or filling ordinary amygdaloidal 

 cavities in the basalt. It is clearly a product of infiltration into these 

 cavities, and not an alteration of a previous mineral, because the walls 

 of the cavities are quite distinct from the mineral. Were it a product 

 of alteration, it might be expected to merge into the rock itself, or such 

 minerals as might be altered to such a composition, such as olivine or 

 augite ; but this is not the case, the olivine and the augite are quite 

 distinct from it. Under the microscope the mineral may be observed 

 to fill up the cavities previously left in the rock; and crystals of 



