H A M 



C "5 ] 



H E L 



species, H.maximus, H. attenuatus, H. 

 intermedius, H. tenuis, H. rotundus, H. 

 compressus. 



HA'MOUS. (hamus, Lat.) Hooked. 



HAR'MOTOME. (from ap/iog, a joint, and 

 TSftvu, to divide.) The Kreutzstein of 

 Werner; Cross-stone of Jameson; Pierre 

 cruciforme of Brochant ; Staurolite of 

 Kirwan. For a description of harmo- 

 tome, see Cross-stone. 



HA'RPA. A genus of shells placed by 

 Cuvier in the family Buccinoida, order 

 Pectinibranchiata, class Gasteropoda. A 

 beautiful genus of shells, distinguisha- 

 ble from all others by the regular Ion 

 gitudinal ribs that mark the external sur- 

 face, in some degree resembling a stringed 

 instrument, from which the name is de- 

 rived. The genus is both fossil and re- 

 cent ; the shells are marine, and are in- 

 habitants of warm climates ; they are 

 easily recognized by the projecting trans- 

 verse ribs on the whorls ; the last of 

 which forms a lip on the margin. 



HA'RPAX. A genus of fossil shells de- 

 scribed by Parkinson. They are of an 

 oblong, and somewhat of a triangular, 

 form. The hinge is formed by two long 

 projecting teeth, transversely crenulated 

 on both sides, and diverging in the form 

 of the letter V on the flat valve. 



HA'STATE. (hastatus, Lat.) Spear- 

 shaped. 



HA'TCHETINE. A variety of bitumen, 

 known also as mineral adipocere, found 

 in the iron ore of Merthyr Tydfil in 

 Glamorganshire. It is insoluble in 

 water, but soluble in alcohol and ether. 

 It fuses at 160. It is of the hardness of 

 soft tallow. 



HAUSMA'NNITE. } Pyramidal manganese- 



HAUSSMA'NNITE. $ ore. The Manganese 

 oxyde hydrate of Haiiy. It occurs in 

 porphyry, in veins, in America and Ger- 

 many. It is of a brownish-black colour. 

 It consists, according to Turner, of 

 98'10 of red oxide of manganese, silica 

 0-34, oxygen 21, baryta, O'll, water 

 0-43. 



HAUYNE. Dodecahedral Zeolite, or Lapis 

 Lazuli. 



HEART-SHAPED. A triangular figure, hav- 

 ing its base emarginate, lateral angles 

 rounded, and lateral margin slightly 

 swoln. 



HEA'VY SPAR. Sulphate of barytes, baro- 

 selenite, or prismatic heavy spar. The 

 Baryte sulphatee of Haiiy ; the Schwer 

 spath of Werner ; and Prismatischer hal- 

 baryte of Mohs. There are several va- 

 rieties of this genus, namely, the compact 

 heavy spar, having a splintery and uneven 

 fracture ; the fibrous heavy spar ; the 

 straight and curved lamellar heavy spar ; 

 the radiated heavy spar ; the fetid heavy 



spar, giving out, on friction a hepatic 

 odour, whence it is also called hepatite ; 

 the earthy heavy spar ; the prismatic 

 heavy spar. 



Heavy spar consists of baryta 66 parts 

 and sulphuric acid 34 parts. It fre- 

 quently contains a trace of silex, alumine, 

 oxide of iron, and sometimes of sulphate 

 of strontian. It occurs in veins, both 

 massive and crystallized, in many parts 

 of England, Ireland, Scotland, and Ger- 

 many, being found in primary, transition, 

 and secondary rocks. It is of different 

 colours. It strongly decrepitates when 

 heated, and fuses into a white enamel, 

 which in the course of some hours falls 

 into powder. One of the most striking cha- 

 racters of this mineral is its great specific 

 gravity, which varies from 4'29 to 4'50. 

 It is from this circumstance it has ob- 

 tained its name. It is harder than crys- 

 tallized carbonate of lime, but may be 

 scratched by fluate of lime. Heavy 

 spar may be confounded with sulphate 

 of strontian, but its specific gravity is 

 greater. After fusion, the enamel pro- 

 duced from heavy spar, if applied to the 

 tongue, produces a taste similar to that 

 of rotten eggs, this does not occur in the 

 enamel of sulphate of strontian. Heavy 

 spar is seldom found in large masses. 

 It is sometimes employed as a flux in 

 metallurgic operations, and is said to be 

 a good base for water colours. 



HE'LICAL. (helice, Fr. t'Xi, Gr.) Spiral ; 

 winding. 



HE'LIOTROPE. (heliotrope, Fr. eliotropia, 

 It. heliotropium, Lat. rjXioTpojriov, Gr. 

 from 77\io and TJOETTW.) 



1. A plant, the turnsole. 



2. A variety of rhombohedral quartz, of a 

 deep green colour, with disseminated 

 spots of yellow and red jasper. It is 

 more or less translucent. Fracture im- 

 perfectly conchoidai. Specific gravity 

 about 2-63. The finest specimens are 

 brought from Siberia and Bucharia. Like 

 agate, it is employed in forming orna- 

 mental articles. 



HE'LIX. (s'Xil, Gr.) 



1. The outer bar, or margin, of the exter- 

 nal ear. 



2. The snail. A globular or orbicular 

 shell ; spire short, convex or conoidal, 

 last whorl ventricose ; opening entire, 

 being wider than long ; no operculum. 

 The helix aspera, or common snail, is a 

 well-known illustration. Parkinson ob- 

 serves of the fossil helix, " Shells of this 

 genus are rarely found in a state of petri- 

 faction. The circumstances of conserva- 

 tion in which they are found are, gene- 

 rally, such as are explicable on the sup- 

 position of their having become involved 

 in the gradually accreting tufaceous mat- 



