MINERALOGY. 



491 



*J- 



Agaric ml. 



eriL 



Gn<rnoslic Situation. It constitutes one of the newer 

 secondary or floetz formations ; is usually found in low 

 situations, and frequently on sea-coasts. It is stratified, 

 and the strata in general are horizontal. It often con. 

 tains flint, which is disposed either in interrupted beds 

 in the chalk, or in globular, tuberose, or tabular masses 

 imbedded in it. It abounds in organic remains, and 

 these are principally of animals of the lower orders, 

 such as echinites, beleninites, terebratulites, pinnites, &c. 



Geographic Situation. It abounds in the south-east- 

 ern part* of England, extends through several pro- 

 vinces in France, occupies great tracts of country in 

 Poland and Russia, U met with on the shores of the 

 Baltic, and in the islands of Zeeland and Uugen. 



Utet. The uses of this mineral are various. The 

 more compact kind* are employed as building-stones, 

 when they are used either in a rough state, or are sawn 

 into blocks of the requisite size and shape : it is burnt 

 into quicklime, and used for mortar in different coun- 

 tries ; thus, nearly all the houses in London are ce- 

 mented with chalk-mortar : it is also employed in 

 great quantities in the polishing of glass and metal*, 

 and whitening the rood of rooms, in the state of whit' 

 ing t ; in constructing mould* to cart metal in ; by 

 carpenter* and others as a material to mark with. 

 When perfectly purified, and mixed with vegetable co- 

 lours, it form* a kind of pastil colour : thus, with lit- 

 mus, turmeric, saffron, and sap-green, it forms durable 

 colours, but vegetable colours that contain an acid, be- 

 com* blue when mixed with it. The Vienna trltilc 

 known to artists i* perfectly purified chalk. It i* used 

 by starch-makers and chemist* to dry precipitates on, 

 for which it is peculiarly qualified, on account of the 

 remarkable facility with which it absorbs water. With 

 iaingUs, or white of eggs, it forms a valuable lute or 

 cement- In the gilding of wood, it is necessary, before 

 laying on the gold, to cover it with a succession of 

 coats of a mixture of whiting and siie. The mineral 

 i* also used as a filtering-stone ; and in a purified state, 

 it i* employed as a remedy to correct acidity in the 

 i*irMTTi. and the morbid states which arise from this. 



FOVRTII SUBSPECIES. 



AGARIC MINERAL, OR ROCK MILK, Jameton. Berg- 

 Milch, Werner. 



External Characters. Colour* *now-white, greyish- 

 white, and yellowish-white. Occur* frequently in 

 crusts, also in loosely cohering tuberose piece*. Dull. 

 Composed of fine dusty particles. Soils strongly. 

 Feels meagre. Adheres slightly to the tongue. Very 

 light, almost supernatant. 



Chemical Characters. It effervesces with acids, and 

 is completely dissolved in them. 



Constituent Parts. It is a pure carbonate of lime. 



Gf agnostic and Geographic Situations. It is found on 

 the north side of Oxford, between the I sis and the 

 Cherwell, and near Chipping-Norton, also in Oxford. 



Firm SUBSPECIES. 



... . , FIBROUS LIMESTONE, Jameson. Fasriger Kalkstein, 



<m iitoos Werner. 



This subspecies i* divided into two kinds, viz. Com- 



mon Fibrous Limestone, or Satin-Spar, and Fibrous Oryctogno- 

 Calc-Sinter. T- 



FIRST KINO. 



COMMON FIBROUS LIMESTONE, on SATIN-SPAR, common 

 Jameton. Gemeiner fasriger Kalkstein, Werner. fibrous 



External Characters. Colours greyish, reddish, and limestone, 

 yellowish-white. Occurs massive, also in distinct con- 

 cretions, which are coarse and fine fibrous, and either 

 straight or curved. Lustre glistening or shining, and 

 pearly. Fragments splintery. Feebly translucent. 

 As hard as calcareous-spar. Easily frangible. Speci- 

 fic gravity 2.70, Pepys. 



Constituent Parts. 



Carbonate of Lime, 95.75 Lime, . 50.8 



Carbonate of Manganese, 4.25 Carbonic Acid, 47.6 



.08.4 



Holme. Pepys, in Kid's 

 Min.vol.i.p. 49. 



Stromeyer says that fibrous limestone contains seme 

 per cent*, of gypsum. 



GeogHottic and Geographic Situations. ]t occurs in 

 thin layer* in clay-slate at Aldstone Moore in Cum- 

 berland ; in layers and veins in the middle district of 

 Scotland, a* in Fifeshire. On the Continent, at Pots- 

 chappel, near Dresden, and at Schneeberg, also in 

 Saxony. 



L'*et.lt is sometimes cut into necklaces, crosses, 

 and other ornamental articles. 



SECOND KINO. 



FIBROUS CALC-SiNTEHj, Jameton. Fasriger Kalk- 

 sinter, Werner. 



External Characters Principal colours white, yel- Fibrout 

 low, brown, grey, red, green, and blue, Sometimes calc-tinter. 

 concentrically and reniformly striped, or it is spotted 

 or clouded. Occurs massive, stalactitic, globular, tu- 

 bular, claviform, fruticose, curtain-shaped, cockV 

 comh shaped, coralloidal, reniform, and tuberose ; also 

 in distinct concretions, which are fibrous, and these 

 are straight, seldom curved, and sometimes scopitbrm 

 or stellular ; also in reniform curved lamellar concre- 

 tions, and seldom in large and coarse angulo-yrami- 

 lar concretions ; very rarely the longish external 

 shapes, as the stalactitic, are terminated by a three- 

 -ided pyramidal crystallization. .Surface generally rough, 

 and seldom fine drusy. Internally glimmering, which 

 peases on the one aide into dull, on the other into 

 glistening ; and the lustre is pearly. Fracture fine 

 splintery. Fragments splintery, or wedge-shaped. 

 Translucent, or only translucent on the edges. 



Constituent Vartt. Lime . 5(j.O 



Carbonic Acid 43.0 

 Water . 1.0100.0 



Bueholz, in Gehlen's Journal, b. iv. s. 425. 



Geognottic and Geogran/iic Situations It is found 



encrusting the roofs, walls, and floors of caves, parti- 

 cularly those situated in limestone rocks. It is formed 

 from water holding carbonate of lime in solution. Caves 

 lined with this mineral occur in almost every country. 

 Maccallister's Cave, in the island of Skve, and those in 

 the limestone hills of Derbyshire, are the most striking 



Accenting to SmeaMn. it mains a* good lime u the batt limettone or marble. 



In the preparation of whiting, chalk u paamtti, an* difiiaed through water, nd the finer prt of the wdiment u then dried ; by this 

 MSB*, the tiliceoua pankkt rc trpuaud, which, by uxic hanlDCM. would icwich the lurfac* of meullk and other mirheif, in the polih- 

 af of which whiting fa wed Aikin'* Cho*. Diction; 



Thi u the AUbwtcr of uie aBcienu. and u by the osdme named Cultareoui Atabatttr, to diitiiiguub it from another 

 gypmo, which they naox Gfftfoml AltUiUr. 



