ÆDELFORSITE.

highest peaks named Adula, whence has been derived the name Adularia.

"Adularia is distinguished from common Felspar by its greenish-white colour, particular colour reflection, complete conchoidal cross-fracture, lamellar distinct concretions, its higher degree of transparency, and by the want of those rents which cross the cleavage obliquely in common Felspar."Jameson, vol. i. p. 289.

For varieties of Adularia, see MOONSTONE, SUNSTONE, VALENCIANITE.

Brit. Mus., Case 30.

M. P. G. Horse-shoe Case, Nos. 955 to 959, 1039.

ÆDELFORSITE, Dana, v. Kobell. Occurs massive, and fibrous or feathery. Colour white or greyish. Transparent or translucent at the edges. Lustre shining. H. 6. S.G. 2.58.

Comp. Neutral silicate of lime, or Ca Si lime 378, silica 62.2 = 100. BB fuses to a white translucent glass. Forms a jelly with acids.

Localities. Edelfors in Smaoland, Sweden; Cjelleback in Norway; Cziklowa, in the Bannat.

Peroxide of iron Oxide of tin.

25.9

20-0

15.0

.

3.8

When heated evolves water and traces of

hydrofluoric acid.

BB swells up and fuses, at the edges only, to a black slag. With borax fuses readily to a dark yellow glass, which is colourless With salt of phosphorus forms when cool. a transparent colourless globule. Locality. The Ilmen range, near Miask, in Siberia; imbedded in Felspar, and associated with Mica and Zircon.

Name. The name (derived from aixón, disgrace) given to this mineral by Berzelius, is in allusion to the inability of chemists, at the time of its discovery, to separate the two substances titanic acid and zirconia, which enter into its composition.

Brit. Mus., Case 37.

ETITES, Pliny. Stones composed commonly of several crusts one within another, and having in them cavities containing loose and moveable matter; either, first, solid and stony, called a Callimus, or secondly, loose, as sand, ochre, chalk, earth, &c., Geode; or thirdly, liquid, Enhydros. (J. Woodward.) AFTONITE. See APHTHONITE.

AGALMATOLITE, Phillips, is a clay or clayslate altered by heat, and by the action and addition of alkalies contained in infiltrating waters holding in solution alkaline silicates, or carbonates derived from the decomposi

Localities.-English. Restormel Royal iron mines, Cornwall; of a pale flesh-colour.Welsh. Glyder Bach, Caernarvonshire.Irish. Lugganure lead-mines, co. Wicklow, (pale green).-Foreign. Norway. Nagyag in Transylvania.

Name. From yαλμæ, an image, and λíos, stone.

AGARIC MINERAL.

Agates are used for burnishers, and are made into mortars for chemical purposes. They are also much employed in a polished state for ornamental articles, as brooches, bracelets, beads, the handles of seals, paperknives, daggers, &c. The brooch-stones sold by the name of Scotch pebbles are true Agates, found in the amygdaloid of Dunbar, and of the Hill of Kinnoul, near Perth; but the stones found in the Isle of Wight and sold in a polished state under the name of Agates, are merely flints from the Upper Chalk, much of the beauty of which is derived from the silicified remains of sponges and other marine bodies.

The colours of Agate, when indistinct, and afterwards in sulphuric acid; the latter may be increased by boiling first in oil, absorbed between the layers, heightens the process carbonising the oil which has been contrast between their different tints.

ex

M. P. G. Horse-shoe Case, Nos. 1102, 1109, 1112.

AGAPHITE. See TURQUOIS.

AGATE. A variegated variety of chalcedonic Quartz, the colours of which are arranged in clouds, spots, or bands. The latter consist of parallel or concentric layers, either straight (ribbon agate), circular, or in zigzag forms, the latter receiving the name of fortification agate from the fancied resemblance of the bands to the angular outline of a fortification.

Agates are found in Scotland, Saxony, Arabia, India, Surinam, &c. in amygdaloid, mostly in the form of hollow balls or geodes, coated inside with Quartz or Amethyst.

Immense quantities of Agate are cut and polished at Oberstein in Rhenish Bavaria, and at Galgernberg in the north of Germany, whence they are exported to all parts of the world.* There is also a manufactory at Katherinenberg in Siberia.

* "The agate trade at Oberstein and Idal has lately undergone a singular change in consequence of a falling off in the supply of the agate nodules. The agates now worked in that district, and sold as native productions, are chiefly obtained from the Brazils, where, on the Paraguay, brought down from the interior by the Rio de la Plata, they are in such abundance as to be shipped for ballast. Notwithstanding the source of supply is

The name is derived from that of the river Achates, whence, according to Theophrastus, agates were first brought.

so remote, agate articles are sold in Germany at prices astonishingly low. One other fact in connection with the agate frauds may be worth recording. Upper Egypt is known to yield agates, though different from those of South America, and much less abundant. Travellers from Europe in passing through that country enquire for these; and, to meet the demand, Brazilian agates are now sent to Egypt, and there sold for Egyptian agates. At Cairo, especially, numbers are thus disposed of to English and other travellers, who purchase them as souvenirs of the country.' - Handbook to the Geology of Weymouth and Portland, by R. Damon; Stanford, 1860.

AGATE-JASPER.

Localities-English. Banner Down, near Bath. Chipping Norton, Oxfordshire. Near Sunderland.-Welsh. Llyn Savaddan, on the river Llynvi, in Brecknockshire. Trevor, near Llangollen, Merionethshire. -Scotch. Near Edinburgh. — Irish. Aghanloo and Curly Burn, in New Red Sandstone. Slieve Gallion, coating flint balls.-Foreign. Near Ratisbon. Switzerland, where it is used for whitewashing houses. The United States, covering the sides of a cave at Watertown.

Name. From its resemblance to agaric (a fungus) in colour and texture.

AGATE-JASPER. A variety of Jasper found in agate-veins.

Brit. Mus., Case 23.

AGATE MOUSSEUSE. Moss Agate. AGATE PÉRIGONE. Fortification Agate. AGATE TERREUSE. See CACHOLONG, FLOATSTONE, &c.

AGATE VERSICOLORE. Variegated Agate. AGATE ZONAIRE. Agate, the layers of which are arranged in concentric curvilinear bands.

AGATHE CORNALINE, La Metherie. See CARNELIAN.

AGNESITE: an earthy steatitic mineral from Huel Coates, near St. Agnes, in Cornwall. It is, probably, an impure Bismuthochre, according to Greg & Lettsom.

AIGUE MARINE. See AQUA-MARINE. AIGUE MARINE DE SIBERIE, Romé de L'Isle. See BERYL.

AIKENITE, Chapman, Dana. Rhombic: occurs in imbedded acicular four or sixsided prisms, indistinctly terminated, and striated longitudinally; also massive.

Colour. When fresh broken dark steelgrey, but soon acquiring a yellowish or pale copper-red tarnish. Opaque. Lustre metallic. Streak blackish-grey. Structure lamellar. Fracture small-grained, uneven; sometimes approaching to conchoidal. H. 2 to 2.5. S.G. 6.1 to 6.8.

Comp. Sulphide of Bismuth, Copper and Lead, or (Cu, Pb) S +3 Bi S3.

Analysis by Hermann, from Beresowsk:
Bismuth

34.87

36.31

10.97

16.50

0 36

0.09

99.00

BB gives off fumes of sulphur, fuses and emits numerous burning globules, and finally yields a globule of lead containing copper, which colours glass of borax greenish-blue. Dissolves in nitric acid with

M.P.G. Principal Floor, Wall-cases 9, No. 465; 20 (Russia).

AIMANT, Beudant. See MAGNETITE. AIMANT DE CEYLON. See TOURMALINE. AKANTHITE, Dufrénoy: (from äzavba, a spine,) a variety of Epidote from Achmatowsk.

AKANTICONE. See EPIDOTE.

AKMIT, Haidinger. See ACHMITE.

ALABANDICUS, a stone "Called after the name of the countrey that yieldeth it, it is black: Howbeit, there is of it to be found growing in Miletus, but not altogether so blacke, for it enclineth or declineth rather to a purple colour. This stone of Miletus will resolve in the fire, and commonly they use to melt it for drinking cups, in manner of glasses."-Pliny, book xxxviii, ch. 7.

ALABANDINE, Beudant, Brooke & Miller. See MANGANBLENDE.

ALABANDINE, Pliny: those carbuncles which were cut and polished at Alabanda, and were called in consequence Alabandine or Alamandine. "Ethiopian Rubies and the Alexandrian, which are found, indeed, among the cliffs of the hill Orthosia, but trimmed and brought to their perfection by the Alabandians. Many authors have written. . that the Alabandines be more darke and blackish than others, and withal rough in hand." — Pliny, book xxxviii. ch. 7.

ALABASTER: is the name by which the fine massive varieties of Gypsum are called. It is a sulphate of lime, composed of sul

huric acid, 46.51; lime, 32 56; water, 20.93. At Volterra and Castellina, in Tuscany, it occurs extremely pure and compact, and is conveyed thence in large blocks to Florence, where it is manufactured into figures, vases, and other works of art, which are exported to all parts of Europe. Twenty years ago there was a great taste for such objects in France, and the material was then obtained from quarries at Lagny, near Paris. In England it occurs in New Red Marl, principally at Ashton-on-Trent, and Chellaston Hill, near Ashbourne, in Derbyshire, at both of which places it is extensively worked for ornamental purposes "The principal demand for this material

usually slightly streaked with red, is by the potters in Staffordshire, who form their moulds of plaster of Paris from it. It is therefore called 'Potter's stone,' and sells at about 9s. per ton of 2,400 lbs. (the long ton). In working the Potter's stone, the fine blocks are selected, and sold to the turners of alabaster ornaments."-(Robert Hunt.) It is also found in large quantities at Penarth, Cardiff, Leckwith, and Lavenock, in Glamorganshire; at Newark, in Nottinghamshire; at Fauld Hill, in Staffordshire; at Old Chine, in Somerset; between Penrith and Carlisle, in Cumberland; and in Monaghan co., Ireland. Alabaster is soluble in 400 to 500 parts of water. When heated it parts with its water of composition, and becomes Plaster of Paris, for which see GYPThis stone is the Alabastrum of the ancients, by whom it was carved into statues and other objects. The name is derived from Alabastron, a village of Egypt. (See ORIENTAL ALABASTER).

SUM.

Brit. Mus., Case 57.

M. P. G. Sides of vestibule, Derbyshire. Large tazza and pedestal, on the eastern side of the hall, from Fauld Hill, Staffordshire. Column against east wall. Column, supporting serpentine vase, west side of the hall. Horse-shoe Case, Nos. 303 and 304.

ALABASTRA AGATATO. A yellow variety of Alabaster found at Sienna.

ALABASTRITES, Pliny. See ORIENTAL ALABASTER. "This Onyx stone, or Onychites aforesaid, some name Alabastrites; whereof they use for to make hollow boxes and pots to receive sweet perfumes and ointments, because it is thought that they will keepe and preserve them excellently well, without corruption. The same being burnt and calcined, is very good for diverse plastres."-Pliny, book xxxvi. ch. 8.

ALALITE. A variety of Diopside from Ala, in Piedmont.

M. P. G. Horse-shoe Case, Nos. 1032, 1033.

ALAUNSTEIN, Werner. See ALUMSTONE. ALBERT COAL, or ALBERTITE. A bituminous kind of Coal found in Nova Scotia, and at Hillsborough, in New Brunswick. Analysis by Slessor:

Volatile matters Fixed carbon

100.00

It yields, on distillation, 100 gallons of crude oil per ton. See MELANASPHALT.

ALBIN, Werner. A white, opaque variety of Apophyllite. found, associated with Natrolite, at Aussig, in Bohemia. Brit Mus., Case 27.

ALBITE, Beudant, Brooke & Miller, Dana, Phillips, Greg & Lettsom. Anorthic. Primary form a doubly-oblique prism. Occurs generally in flat twin crystals.

Colour. Usually white; sometimes grey, green, or brown. Translucent to opaque. Lustre vitreous, pearly on cleavage planes. Streak white. Brittle. Fracture uneven. H. 6. S.G. 2:59 to 2.65.

BB behaves like Felspar, but imparts a more distinct yellow colour to the flame. Not acted on by hot acids.

Localities.- English. Cornwall; at Huel. Friendship on Quartz, and in white translucent crystals at Tintagel, near Camelford, Fig. 5; Beverley, Yorkshire; in greenstone.- Welsh: Tremadoc, Caernarvonshire-Scotch. Near Edinburgh, in greenstone.-Ireland. In very perfect, white translucent twin-crystals at Ross, and in the granite of Slieve Corra, one of the Mourne Mountains. The forms found in the United Kingdom are represented in Fig. 5.- Foreign: The Tyrol, in large transparent, colourless crystals, with Pearl-spar; St. Gotthard, in white translucent twins; Arendal, in Norway, with

ALEXANDRITE.

Epidote and Garnet; Greenland, with Eudyalite and Hornblende; Massachusetts, U. S., with Tourmaline; Siberia; Norway; Sweden; Bohemia; Oisans, in Dauphiny; and elsewhere.

Name. From albus (white), in allusion to its colour.

Brit. Mus., Case 30.

M. P.G. Horse-shoe Case, No. 953. Albite is a soda Felspar, a small portion of the soda being sometimes replaced by potash and lime. It is frequently a constituent of granite, and, more frequently than common Felspar, of syenite and greenstone (as in the rocks round Edinburgh); but it often occurs associated with the latter in the same granite, when it may be distinguished by its greater whiteness and translucency. Thus, in the granite of Pompey's Pillar, and the block on which the statue of Peter the Great in St. Petersburg is placed, the Albite presents a greenish-white colour, while the Felspar is flesh-red.

ALEXANDRITE. A variety of Chrysoberyl found in mica-slate with Beryl and Phenacite, 85 wersts from Ekatherinenberg in the Ural. It is of an emerald-green colour by reflected light and columbine-red by transmitted light. The colour is supposed to be produced by the presence of oxide of chrome. Named after Alexander I., Emperor of Russia.

Brit. Mus., Case 19.

ALGERITE. An altered form of Scapolite. Occurs in slender square prisms imbedded in Calc-spar. Colour yellowish to grey. Usually dull. Brittle. H. 3 to 3.5: of more altered crystals 2.5. S.G. 27 to 2.78. Analysis by T. S. Hunt:

Silica Alumina

49.82

24.91

Silica

Lime

75.0

16.0

7.5

98.5