in this Case. It is remarkable for containing crystalline calcium sulphide, associated with Enstatite and Augite.

In Case B. are displayed, on the left extremity of the Case, the Siderolites, while the rest of the space is occupied by the Aëro-siderites. The former are masses of meteoric iron containing stony matter; the latter consist of the metallic alloys of iron and nickel with small amounts of other metals, known as "meteoric iron." They also contain mechanical admixtures of compounds of these metals with phosphorus, and also with sulphur. Among the specimens of the former class, is the mass found at Breitenbach in Bohemia, in 1861. It contains Silica crystallised in the orthorhombic system, associated with a ferriferous Enstatite (Bronzite), that is in some cases well crystallised. The crystalline structure of the meteoric iron masses is effectively shown by the etching of their polished surfaces. On the north side of this room is seen the vast mass of meteoric iron found at Cranbourne, near Melbourne, in Australia, presented by James Bruce, Esq., and weighing above 3 tons. At the east end of the gallery is one weighing 1,400lbs., presented by Sir Woodbine Parish, found on the Gran Chaco, South America.

The Collection of Minerals is arranged in four principal Divisions.

These are

DIVISION I. The Native Elements. Cases 1, 2, 3, 4 (i.)

DIVISION II. The Compounds of Metals, with Elements of the Arsenic Group (the Arsenoid elements, viz. Bismuth, Antimony, and Arsenic); or with elements of the Sulphur Group (the Thionids, viz. Tellurium, Selenium, and Sulphur); or with elements belonging to both groups. Cases 4 (ii.) to 12 inclusive.

DIVISION III. The Compounds of Metals with elements of the Chlorine Group (the Halogen elements-Iodine, Bromine, Chlorine and Fluorine). Cases 13 and 14.

DIVISION IV. Compounds of elements with Oxygen. Cases 15 to 60.

These Divisions are again subdivided into sections and classes, the latter embracing the minerals which fall under the same general chemical denomination; as, for instance, the salts of the same acid or of a group of acids chemically and crystallographically equivalent to each other. Each class is further separated into distinct chemical series, the minerals included in any series being such as are designated by the same or equivalent typical formulæ. Subordinated to this chemical system of classification is the final distribution of the several homotypical species of each chemical series, into distinct crystallographic series, arranged according to the crystalline system to which they belong; the order of sequence of these systems being-1st, the Cubic System; 2nd, the Dimetric or Pyramidal System; 3rd, the Trimetric or Ortho

rhombic System; 4th, the Hexagonal or Rhombohedral System; 5th, the
Oblique or Clinorhombic System; 6th, the Anorthic System; and finally,
Amorphous substances, that either present no crystalline forms, or
the forms of which, if they be crystalline, are not determinable. In
the following observations the term "group
" will be reserved to con-
nect Minerals, whether individual species, series, or classes, which pre-
sent such a community of physical and other characters as imparts to
them a sort of family resemblance.

DIVISION I. THE NATIVE ELEMENTS.

DIV. I.

In Cases 1, 2, 3, and the first half of 4, are arranged such of the Cases 1, 2, elementary forms of matter as are found occurring in nature in the un- 3, 4 (i.) combined state. These native elements, which form but a small proportion of those the chemist has eliminated from the Mineral Kingdom, are arranged in sections, of which the first is that of the native metals and their alloys.

Of the series of native metals crystallising in the cubic system the various forms of Copper, Silver, and Gold are the most important; and Cases 1, 2. crystals of these metals are exhibited, remarkable for the perfection of their forms, or conspicuous for their size. The crystallised copper from Siberia and from Lake Superior, the silver in crystals from Kongsberg and from Freiberg, the suite of specimens of gold from Merionethshire and other British localities, two unique nuggets of crystallized gold from Case 2. the MacIvor Diggings, in Australia, and one from California, are especially worthy of remark. Besides these, will also be seen native foil of silver and of gold: moss-like filamentary aggregations of copper and of silver; nuggets, and washed grains of gold, and specimens of all these metals, in which a simple crystalline form, by being repeated or prolonged along particular axes has built up dendritic, ramose, capillary, and other singular kinds of structure. Among the specimens of gold and of electrum, or argentiferous gold rich in silver, from Transylvania, are some worthy of notice from the sharpness of their crystalline forms. Native lead from Sweden, and a crystalline nugget of platinum containing metallic iron and presenting magnetic polarity, given by H. I. H. the Grand Duke of Leuchtenberg, are exhibited in Case 3. The rhombohedral series of metals includes an isomorphous group-the Arsenoids namely, Arsenic, Antimony, and Case 3 (i.) Bismuth, with which its crystalline form, rather than its chemical analogies, associates the rare native element Tellurium.

Next to the metals are arranged the Metalloids, a section including Case 3 (ii.) the carbon group and the sulphur group. In the former, elementary Carbon is illustrated in its two allotropic mineral forms: Diamond and Graphite. Of the Diamond, a large and extremely choice series of crystals is exhibited, together with models of the most famous for their size and history of the specimens of this, the hardest and most resplendent of gems.

Div. 1.
Case 4.

Of Sulphur, large and splendid yellow crystals are exhibited from Conil, near Cadiz, and fine specimens from Sicily. The glazed front of Case 2 contains specimens belonging to this division, of extraordinary size and beauty.

DIV. II. DIVISION II. COMPOUNDS OF THE ARSENOID AND THIONID ELEMENTS.

Cases 4 (ii.) to 10 (i.)

Leaving the native elements, we enter upon minerals which are the products of the chemical combination of the elements with each other; but the transition is not an abrupt one. The alloys, or mixtures of metals of one and the same group, were associated in the first division with the metallic elements that compose them. But where metals belonging to distinct chemical groups are combined, they cannot be classed with the free elements. Such are the combinations of Arsenic, Antimony, and Bismuth with metals of other groups, and they (the arsenides, antimonides, &c.) accordingly take their places as the first section of Division II and will be found arranged in the latter half of Case 4.

Next in order to these are placed, as a second section of Division II., the compounds of metals with the "thionid elements;" and accordingly the tellurides, selenides, and sulphides are displayed in Cases 5 to 9 inclusive.

These are succeeded by a third section of this division, namely, by Minerals to form which compounds belonging to each of the former sections are combined together.

These three sections may be severally represented by their prominent members, the arsenides, the sulphides, and the arseno-sulphides. Section i. The first of these sections comprises the cuprous arsenides, such Case 4 (ii.) as Domeykite, the tricuprous arsenide; also, the antimonide of Silver or Dyscrasite, diargentous antimonide. Besides these there are included in this section several compounds of Iron, Cobalt, and Nickel. Nickeline, called also "Copper-Nickel," from its colour, is a rhombohedral mineral, the nickel arsenide. Chloanthite is the nickel diarsenide and Smaltine, or "tin-white Cobalt," the cobalt diarsenide, of which Safflorite is a variety, containing Iron in place of a part of its Cobalt. These minerals are cubic in crystallisation, but some of the substances which constitute them are also found in orthorhombic forms, affording examples of dimorphism. Thus the nickel diarsenide, when thus occurring in crystals of the orthorhombic system, is the mineral Rammelsbergite (of Dana), and Leucopyrite is a corresponding iron diarsenide,

In this section is also included the cobalt triarsenide, Skutterudite. Section ii. The second section includes the various compounds of Sulphur. Selenium, or Tellurium-the Thionid elements-with the metals, Silver, a monad element, and Copper, a metal that in one group of its salts plays the part of a monad element, contribute to form a small group in this section of the type M, E. Eucairite is a selenide of Silver and Copper, and Crookesite is a selenide of Copper and Thallium.

Petzite is the Silver (diargentous) telluride, Naumannite the corre- Div. II. sponding selenide of Silver, while Argentite is the sulphide of Silver. Case 5 (i.) The latter are cubic in crystallisation, but the silver sulphide is a dimorphous mineral presenting itself as Acanthite in forms belonging to the orthorhombic system. To this system belongs also Copperglance, a valuable ore of Copper, the "cuprous" (or dicupric) sulphide. Among the other important minerals in this section, a cubic series Case 7 (i.) of monosulphides occurs which includes two commercially very im- Cases 5 (ii.) portant ores Galena, the lead sulphide, and Blende, the zinc and 6. sulphide.

A Rhombohedral series includes Covelline, the cupric (monocupric) sulphide, Cinnabar, or mercuric sulphide, the unique ore of the important metal Mercury. Millerite is the nickel monosulphide, and Greenockite, a rare mineral in bright yellow crystals, consists of the corresponding cadmium sulphide..

Cases 7 & 8.

There is also an important series of disulphides wherein Hauerite Case 8. and Iron-pyrites, which are severally the manganese and the iron disulphide, are cubic, while as Marcasite the latter compound is orthorhombic in crystallisation. These two forms of the iron disulphide are frequent and familiar minerals, Iron-pyrites being conspicuous for its sharply defined forms, and Marcasite, or "White Ironpyrites," for the fantastic groupings in its crystallisation that have obtained for it the various names of Spear pyrites, Cockscomb pyrites, &c.

Molybdenite (Mo S2) and Realgar (As, S2) are severally molybdenum Case 9. and arsenic disulphides; the former a rhombohedral, the latter an oblique mineral.

Here also is included Laurite, the rare ruthenium sulphide.

Among the trisulphides we find some important compounds of the triad elements crystallising in the orthorhombic system. They are Case 9. Orpiment, or arsenic epideutosulphide (As, S.), and the two isomorphous epideutosulphides of Bismuth and Antimony, Bismuthite (Bi, S.,) and Antimonite (Sb, S). Of both the last minerals, and in particular of Antimonite, very fine specimens are in this Table Case. Antimonite is an important source of the metal Antimony.

The third section of the division is composed of minerals wherein cer- Sect. iii. tain arsenides, &c., of Section i. are combined with sulphides of Section ii., or which may be looked on as the result of a replacement of half the Arsenic of the minerals in the former section, by its equivalent of Sulphur. Of these there is a cubic series, including Cobaltine, or Case 10. Cobalt-glance, the "Silver White Cobalt" of early mineralogists, a Cobalt arseno-sulphide, Co (As,, S); or Co As,; Co S. In Gersdorffite, or Nickel-glance, and Ullmannite or Antimonial Nickel-glance, half the sulphur in a nickel disulphide is replaced by Arsenic and by Antimony respectively.

In this section, also, the minerals of this chemical type exhibit a dimorphism similar to that of Pyrites and Marcasite among the disulphides of Section ii., and of Rammelsbergite and Chloanthite among the diarsenides of Section i.; for in Mispickel and Glaucodote we Case 10.

Div. II. find arseno-sulphides of Cobalt and Iron of the same chemical type as Cobalt-glance, but crystallised in the orthorhombic system. Thus the three homotypic series of cubic diarsenides, disulphides, and diarsenosulphides belonging to the three sections of this division might be treated as a single group, while the three corresponding trimetric series may be looked on as another such group.

Sect. iv.

Cases 10, 11, 12.

Case 10.

Case 11.

Case 11.

Case 11.

Case 12.

Besides the three sections already described, this division contains a fourth, wherein metallic sulphides are so combined with sulphides of Arsenic, Tin, Iron, &c., as to produce a series of sulphur salts; in the constitution of which Sulphur plays the part which Oxygen plays in the ordinary oxygen-salts. This section is a numerous one in point of species, and the following are a few minerals included in it that are especially worthy of note.

In one (and that a somewhat ambiguous) class of these Salts, Iron, either as an iron epideutosulphide (Fe, S.) or as iron disulphide (Fe S2), would seem to enter as a constituent of the "acid" ingredient. In this class we meet with two important copper ores, the largely worked Chalco-pyrites or Copper-pyrites, and Erubescite or Purple Copper-ore. Of both these minerals, there are crystallised specimens from Cornwall; and massive pieces from Tuscany are seen in the front of Case 7. The rare mineral, Sternbergite, consisting of Iron, Sulphur, and Silver, belongs also to this class; while Linnæite, or "Cobalt-pyrites," (Co3 S4, cobalt epitrisulphide,) is a sulphur-compound of Cobalt, exactly analogous to the oxygen-compounds termed the "magnetic oxides" of Iron or Manganese,

Tin-pyrites is a bibasic cuprous sulphostannate, containing Iron and Zinc, being a salt of the tin disulphide Sn S2, (sulphostannic acid).

The largest class of the sulphur salts is that consisting of sulpharsenites, sulpho-bismuthites, and sulph-antimonites. Among these Tetrahedrite (Fahlore or Grey Copper), is noticeable as a most important ore of Copper. It is a sulph-antimonite of that metal, in which copper sulphide is frequently replaced by small amounts of silver sulphide, and is also associated with sulphides of Iron and Zinc. In some of its varieties, as in Tennantite, the Antimony epideutosulphide is entirely, and in others partially, replaced by an equivalent of Arsenic sulphide. The argentiferous Tetrahedrite is a valuable ore of Silver. Remarkable specimens of Bournonite, a tri-basic sulph-antimonite of Copper and Lead from the Herod's-foot mine in Cornwall, are here in juxtaposition with those from the Hartz, and from Traversella. The so-called Red Silvers, a group of isomorphous rhombohedral minerals, are the tri-basic sulphantimonite and sulpharsenite of Silver, Pyrargyrite and Proustite; sometimes in a comparatively isolated state, but more frequently blended together in various proportions. Beautiful as well for their forms as for their blood-red colours, that are deeper in tint according as the antimony preponderates over arsenic, they constitute one of the more precious of the ores of Silver. The specimens of Pyrargyrite and Proustite exhibited in Case 12, and in particular those of the latter mineral from Chili, are extremely fine.