QUA 



21fi 



RAD 



found in every variety of form, although 

 in its composition it varies but slightly. 

 When crystallized, it usually occurs in 

 six-sided prisms, terminated by pyramidal 

 points ; but it also occurs in many deriva- 

 tive forms, its primitive being a rhom- 

 boid. It scratches glass, of which it is 

 an essential ingredient ; it gives sparks 

 with steel in great abundance. Hardness 

 = 7-0. Specific gravity = 2-5, to 2'7. 

 Its lustre ranges from splendent to glim- 

 mering, and is vitreous. Fracture con- 

 choidal. Brittle and easily frangible. It 

 exhibits double refraction, which must be 

 observed by viewing an object through 

 one face of the pyramid and the opposite 

 side of the prism. It is infusible before 

 the blow-pipe, even when the flame is 

 excited by oxygen. Before the compound 

 blow-pipe a fragment of rock crystal 

 fuses instantly into a white glass. Quartz 

 is very generally distributed, and, as far 

 as our knowledge extends at present, ap- 

 pears to be the most abundant mineral in 

 nature. It occurs in every rock, from 

 granite to the newest secondary forma- 

 tion ; it is found in every district of the 

 globe. When mixed with alkalies quartz 

 melts easily, and forms glass. It is not 

 acted upon by any acid but the fluoric. 

 Quartz often encloses, or is mixed up 

 with foreign substances, from which cir- 

 cumstance it assumes great varieties of 

 colour. Many of the precious stones 

 consist of simple quartz combined with 

 some colouring matter. Among these 

 we may place the amethyst, cats' -eye, 

 opal, Bristol diamond, Scotch topaz, &c. 

 Quartz exists in veins intersecting moun- 

 tains, and it sometimes forms large beds, 

 and even entire mountains, which are 

 composed of this mineral in grains united 

 without a cement, called granular quartz. 

 Combined with alumine and iron, quartz 

 loses its translucency and passes into 

 jasper. When rubbed, quartz yields a 

 peculiar odour, and a phosphorescent 

 light. Quartz is a constituent of granite. 



Qu A' RTZOS E. ) Containing quartz; com- 



QUA'RTZY. $ posed of quartz ; resem- 

 bling quartz ; having the properties of 

 quartz. 



QUATERNARY. (quaternarius, Lat. the 

 number of four ; quaternaire, Fr.) Con- 

 sisting of four. In geology, a term ap- 

 plied to the upper tertiary strata, or those 

 which are supposed to be of later forma- 

 tion than any of the strata in the Paris or 

 London basins. The faluns, or marls of 

 Tourraine and the Loire, are quaternary 

 formations. 



QUI'CKLIME. This may be obtained by 

 exposing chalk, limestone, or any calca- 

 reous substance, for a length of time, to 

 full red heat, whereby the carbonic acid 

 and the water which were previously in 

 combination are expelled. 



QUI'CKSILVER. See Mercury. 



QUI'NARY. (quinarius, Lat. quinaire, Fr.) 

 Containing five ; applied to things ar- 

 ranged in "order by fives. 



QUI'NATK. In botany, applied to com- 

 pound leaves when composed of five 

 leaflets. 



QuiNdUA'NGULAR. (from quinque, five, 

 and angulus, an angle, Lat.) Having 

 five corners or angles. 



QUINQUECA'PSULAR. (from quinque, five, 

 and capsula, a capsule, Lat.) In botany, 

 applied to a flower having five capsules. 



QUINQUEDE'NTATE. (from quinque, five, 

 and dens, a tooth, Lat.) Five-toothed. 



QUINCIUEFO'LIATED. (from quinque, five, 

 and folium, a leaf, Lat.) Having five 

 leaves. 



QUINQUELO'BATE. } (from quinque, five, 



QUINQUELO'BED. 5 an< i lobus, a lobe, 

 Lat.) In botany, applied to parts which 

 are divided to the middle into five distinct 

 parts or lobes. 



QUINQUELO'CULAR. (from quinque, five, 

 and loculus, a cell, Lat.) Five celled ; 

 having five cells. 



QUINCIUEVA'LVULAR. (from quinque, five, 

 and valves, doors or valves, Lat.) Having 

 five valves. 



R 



RACE'ME. (racemus, Lat. a bunch of ber- 

 ries.) A term used in botany to express 

 a kind of inflorescence, when all the buds 

 of a newly-formed axis unfold into flow- 

 ers, each having a stalk ; a raceme con- 

 sists of numerous flowers, rather distant, 

 each on its own proper stalk, and all 

 connected together by one common pe- 

 duncle. 



RADIA'TA, The name given to the fourth 

 great division of the animal kingdom, in 



consequence of the radiated form of the 

 body which is so apparent in some of the 

 classes which compose it. This division 

 comprises five classes, namely, Echi- 

 noderma, Acalepha, Polypiphera, Pori- 

 phera, and Polygastrica. The radiata are 

 amongst the most frequent organic re- 

 mains in the transition strata, and they 

 present numerous forms of great beauty. 

 Radiata have also been called zoophyta. 

 They form the lowest division of the 



