GiTS. 



phate of soda and Boro-calcite. America : 

 the oldest Gypsums in America occur near 

 the base of the Palaeozoic series in the so- 

 called Calciferous Sand-rock of Canada ; it is 

 occasionally met with in the Clinton and 

 Niagara groups, and in the Onondaga 

 salt-group in the Upper Silurian rocks of 

 Canada and New York, sometimes accom- 

 panied by sulphur.* 



Name. The word Gypsum is derived from 

 yv-^o;, the name by which the substance, 

 both in its burnt and native state, seems to 

 have been known to the ancients, who ob- 

 tained their supplies chiefly from Cyprus, 

 Phoenicia and Syria, and applied it to the 

 same purposes as the moderns. Theo- 

 phrastus says, "The stone from which 

 Gypsum is made, by burning, is like 

 Alabaster ; it is not dug, however, in such 

 large masses, but in separate lumps. Its 

 viscidity and heat, when moistened, are very 

 wonderful. They use this in buildings, 

 casing them with it, or putting it on any 

 particular place they would strengthen. 

 They prepare it for use, by reducing it to 

 powder, and then pouring water on it, and 

 stirring and mixing the matter well together 

 with wooden instruments : for they cannot 

 do this with the hand because of the heat. 

 They prepare it in this manner immediately 

 before the time of using it ; for in a very 

 little while after moistening, it dries and 

 becomes hard, and not in a condition to be 

 used. 



"This cement is very strong, and often 

 remains good, even after the walls it is laid 

 on crack and decay, and the sand of the 

 stone they are built with moulders away : 

 for it is often seen, that even after some 

 part of a wall has separated itself from the 

 rest, and is fallen down, other parts of it 

 shall yet hang together, and continue firm 

 and in their place, by means of the strength 

 of this matter which they are covered with. 



" This Gypsum may also be taken off from 

 buildings, and by burning, again and again, 

 be made fit for use. It is used for the 

 casing the outsides of edifices, principally in 

 Cyprus and Phoenicia; but in Italy, for 

 whitening over the walls, and other kinds 

 of ornaments within houses. Some kinds 

 of it are also used by painters in their 

 business; and by the fullers, about cloths. 



" It is also excellent, and superior to all 

 other things for making images ; for which 

 it is greatly used, and especially in Greece, 



* See Memoir on the Formation of Gypsum 

 and Magnesian Rocks, by T. Sterry Hunt. Am. 

 Jour. Science and Arts, vol, xxviii. 



HACKED QUARTZ. 167 



because of its pliableness and smoothness." 

 — Theophrastus, cxii. to cxvi. 



Brit. Mus,, Case 54. 



M. P. G. (See Alabaster, and Arago- 

 NiTE),Case 10 in Hall. Horse-shoe Case,Nos. 

 216, 281 to 311, No. 286 specimen from Rein- 

 hardtsbrunn in Gotha, presented by H.R.H. 

 Prince Albert. Upper Gallery, Wall-case 

 40, Nos. S3 to 42, 



Gypsum Selenites, Wallerius. See Se- 



LENITE. 



Gyrasole of Kirwan. A variety of 

 Oriental Sapphire. " Its colour is white 

 with a slight tinge of red, and a still lighter 

 of blue, which gives it some resemblance to 

 Chalcedony." 



Gykolite, Greg §• Lettsom, Brooke §• 

 3Iiller. Gyrolith, v. Kohell, Namnann. 

 Occurs in spherical lamellar radiations, 

 which are translucent when first found, but 

 soon become opaque, or are only translucent 

 in thin plates. Colour white, with a vitre- 

 ous lustre when fresh, which turns to pearly 

 on exposure to the air. Very tough. H. 

 3 to 4. 



Comp. 3Ca Si + 4H = silica 53-29, lime 

 32-86, water 13*85 = 100. 



Analysis, by Anderson ; 

 Silica . 

 Alumina 

 Lime . 

 Magnesia 

 Water . 



. 50-70 

 . 1-48 

 . 33-24 

 . 0-18 

 , 14-18 



99-78 



Localities. — British. The Storr, nine miles 

 from Portree, in Skye, in the cavities of a 

 very compact basalt; also Quirang and 



Lyndale;. near Loch Screden, in Mull 



Foreign. Greenland, at Karartut; Disco 

 Island, near Godhavn ; and at Niakomak, 

 Omensnaksfiord, Faroe. 



Name. The name, derived from >-C^ee?, a 

 circle, and >-i8o?, stone, has reference to the 

 spherical disposition of the mineral. 



Brit. Mus., Case 28. 



H. 



Haar Salz, Werner. Magnesia- Alum. 

 See Alunogen. See also Hair Salt. 



Haarformiges Rothkupfererz, Wer- 

 ner. See Chalcotrichite. 



Haarkies, Mohs, Werner. See Mille- 



EITE. 



Habroneme, from «^go?, delicate,an(i v-^'^a, 

 thread or Jibre. 

 Hacked Quartz, Bakewell A variety 

 M 4 



