The following Mineralogical Account of Matlock and the
vicinity was furnished by Mr. Mawe, whose prompt and
very obliging attention to my application to him for it,
marks a liberality of mind that it is " devoutly to be
wished " was generally possessed by the scientific circle.
Considering the communication a valuable acquisition to
this little volume, the liberal manner in which it was
made is therefore entitled to my warmest thanks.

" PERHAPS," says Mr. Mawe, " there is not any situation in this kingdom so peculiarly adapted for the study of Mineralogy as Matlock Bath. It is in the immediate vicinity of the mines, and exposes a great variety of stratification, very interesting to the geologist.*
The mines are chiefly worked for Galena, or sulphuret of lead. It consists of the following varieties; massive, striated, granular, compact, chrystallized, in a variety of forms. These specimens are sometimes coated with a loosely cohesive powder, or sprinkled with small chrystals of white carbonate of lead, which is also found in a mas-

sive state, and in acicular, and blade-like crystals, imbedded in a loose earthy matter.
Green phosphate of lead, and that very rare mineral, muriate of lead, are found in this neighbourhood ; also earthy white lead ore.

The ores of zinc are found here in great variety. Blend or sulphuret of zinc ; called by the miners Black Jack, massive, and crystallized generally in tetrahedrons indeterminately formed, or confusedly grouped.

Calamine, or carbonate of zinc, occurs massive, botroydal; radiated, cellular, and coating calcarious crystals, which it totally decomposes, and takes their form.

Oxide of zinc in hexagonal tables, elegantly grouped.

A beautiful variety of plumose, or cupreous zinc, of a fine green colour, forming diverging spheroidal tufts, is peculiar to the Rutland Cavern. It has never been met with in any other place.

There are traces of copper, in the form of earthy malachite, but it is of little importance.

Iron pyrites is found in abundance, both massive and crystallized, in various forms. Sometimes the crystals are so formed together as to appear something like wheels, which is called by the miners clock-work, and cock's-comb pyrites.

It occurs also with copper pyrites at his Grace the Duke of Devonshire' s mine, at Ecton. Both are brilliantly crystallized, and sometimes richly irridiscent.

Manganese is found here in the state of black oxide, with iron, and calcareous spar.

The calcarious fossils of this neighbourhood are peculiarly interesting, and exhibit a double refraction, which singular property has but lately been accounted for. The most common form is the double six-sided pyramid, called billet spar, and dog-tooth spar. The primitive rhomb is sometimes met with, which passes into an infinite variety of modifications.

Stalactites are found of great beauty and diversity of colour ; some varieties are curiously zoned, forming the oriental alabaster. A green variety is sometimes (though rarely) found; its colouring matter has not been accounted for. Dr. Kid supposes it to be oxide of zinc.

Fluate of lime occurs in abundance, possessing great beauty and variety. It is generally crystallized in cubes; sometimes one cube is formed upon another, and the surface of the interior one is often sprinkled with brilliant crystals of iron pyrites. Visitors are often told that these are gold and silver spars. The cubic crystals of fluor are sometimes bevelled on the edges. They are often formed upon compact barytes, and in one mine the fluor and barytes are alternately stratified.

Fluor is also found earthy and granular, of various colours.

Snow-white sulphate of lime is found in the Cumberland Cavern, mammilated upon limestone. The hair fossil, or capillary gypsum is no longer found ; but indications are favourable in the Rutland Cavern, where it is expected to be met with in the present course of working.

Barytes (which is here called Cawk) is met with in considerable quantity, consisting of the following varieties : Earthy, in the state of a fine powder, generally coating other minerals. Compact, having frequently a spheroidal appearance, with a rough surface, caused by small projecting crystals. Foliated, is often formed in rhombic crystals, variously modified, which are sometimes curiously interwoven amongst each other.

Radiated, is composed of long needle-Iike crystals diverging from a centre.

Arborescent appears to be composed of a curious aggregation of rhombic crystals, which branch out in a singular manner.

Barytes associates with lead ore, and its attendance is considered favourable by the miners.
Silex, of various forms and colours, is found in considerable quantity, and is called Chert. It often contains fossil corral, and eutrochi, or screw stone.

Quartz crystals are found imbedded in the limestone, in the form of a six-sided prism, with a pyramid at each end, some of which are singularly distorted, and quite transparent. These are called Derbyshire diamonds.

lnflammables. That rare mineral, elastic bitumen, which is almost peculiar to Castleton, has been found here with lead ore and fluor.

Compact bitumen, or mineral pitch, occurs in small spherules in the cavities of limestone; and petrolium is found in its minute fissures.

The stratification of the rocks in this neighbourhood are very interesting. The limestone alternates with the toadstone, which is finely exemplified in the Rutland Cavern. Many varieties of the limestone are worked as marble, under various names. The entrochi marble is full of marine exuvia. Porphyritic marble is of a dark colour, and full of very small white fossils, which give it a porphyritic structure.
Corral marble is composed of fossil madrepore. Black marble is met with here; but at Ashford, on the estate of his Grace the Duke of Devonshire, it is much finer, and is found in great abundance.

Toadstone is greatly varied. Some is of a bright green colour, with white streaks or spots of calcareous spar, quartz, &c. ; others contain red jasper, &c. It also migrates into basalt and wack.

Magnesian limestone, and black chert; form considerable beds.

Schistus is always found above the limestone, and sandstone, of various kinds and colours above the schistus.
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