FLOOR.] 
MINERALS. 
51 
and themselves "of rarity ; much uncertainty, however, still attaches 
to the chemical formulae of several of these species. The titanates, Case 51. 
the tantalates, and niobates, and these combined with silicates, 
zirconates, and stannates, thus link the silicates to the molybdates Case 52. 
and tungstates, and these, in turn, are followed by the class of chro- 
mates and vanadates, and the sulphates. The suite of specimens Cases 51 
of Perofskite from Siberia, the crystals of Eudyalite, of Columbite, of and 52. 
Fergusonite, and of Pyrrhite, and the specimens of Tscheffkinite, are 
especially observable for their excellence or their rarity. Among the an- Cases 53 to 
hydrous species in the sulphates, attention may be called to the specimens 55. 
of Celestine (sulphate of Strontium) from near Bristol, and to the Angle- 
site (sulphate of Lead) from Pennsylvania and from Monte Poni. Gyp- 
sum, or Selenite, the hydrated sulphate of Calcium, is an important 
mineral as yielding Plaster of Paris by the expulsion of its water. A 
magnificent specimen of this mineral, as remarkable for its size as for the 
grouping of its crystals, presented by His Eoyal Highness the late 
Prince Consort, ornaments a window in Room II. It was found at 
Eeinhard's-brunn, Saxe-Coburg. 
Adjoining these are a few minerals of the greatest rarity and inte- Cases 56 
rest. The crystals of Linarite are unique, and the specimens of Cale- and 57. 
donite and Lanarkite, of the sulphato-tricarbonate of lead, Leadhillite, 
and of the rare mineral Connellite, are among the finest known of 
these British species. 
The borates and the class of nitrates occupy part of Case 50 ; and Cases 56 to 
thence to Case 60, the Cases are occupied by the class which includes 60. 
the phosphates and arseniates, in which the isomorphism of the corre- 
sponding compounds of the arsenoid element Phosphorus, and of 
Arsenic, is so complete that the salts of their acids cannot be well 
classified apart from each other. 
Here may be seen fine crystals of Erythrine, the beautiful arseniate 
of Cobalt; specimens of Haidingerite (Case 57), and of Erinite (Case 
57); crystals of Lazulite (Case 58); the suites of Uranophyllite (phos- 
phate of Copper and Uranium), and of Autunite ; the beautiful blue 
Cornish Mineral Liroconite; and splendid specimens of Apatite, Case 60. 
Mimetesite, and Pyromorphite. 
As an Appendix to the Collection, two Half Table Cases in Tioom I., 
contain certain organic compounds, which as occurring in the earth with 
constant and definite characters, independent of organic structure, find 
their place in a Mineral Collection. Among these, Amber, in ancient 
times ranking in value with the gems, is here exhibited in a large 
series of specimens. 
In Iloom II. will be seen two Half Table Cases adjoining the wall, 
in which is arranged an extensive and instructive series of pseudo- 
morphous minerals. They illustrate the decomposing influences to 
which many minerals have been subjected, and they throw valuable 
light on the order of succession in which, and the conditions under 
which, particular minerals have been formed and deposited. 
NEVIL STORY-MASKELYNE. 
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