t68 EARTHS. SILICEOUS. 55. Quantum* 



b. The pyramid double. Born. ind. i, tab, 2./", 9* 



c. The pyramid regular. 



d. The pyramid with the alternate faces larger. 



e. The pyramid with one face larger than all the others. 

 And. Br. a^d. Schiveiz tab. W.f. h. 



f. The pyramid with all the facefe unequal, 



4. The prifms terminating at each end in a 6-fided pyramid not 



ftriate. Gmel. jy/t^ nat. 3, p. 445, /. v^f. i. 



a. With the faces equal, 

 b- With the faces unequal. 



5. The prifms with flraight margins. 



6. The prifms with all or fome of the margins twilled outwardly 



towards the bafe. Syst nat. xii. 3,/>. 84. », 2« b. 



7. The prifms with all the faces unequal^ 



8. The cryftil folidi | 



9. The cryftal hollow within. 



Nitrum inan6. 6'^, nat. xii. 3. /• 85. «. 4. 

 Aman,acad. \% ^.478. n, 14, tab id. f. 12* 

 Wall. /yd. mtn. I, /. 218. «. 9. d. 



a. The hollow of the cryftal empty, 



b. The hollow inclofing a bubble of air, a drdp of wat^cr, a 

 lefler cryftal, or fome other folfile. 



!o. The cryftal with a thicker prifm felted on athinncr* 

 Born. ind. fofs. I f. 22. tab.t, f.\. 



ii. The thinner prifm with a double broader pyramid placed on 

 it, with 2 intermediate unequal globules. 

 Born, ind, fofs, l. p. 23. tab, 2. f, 6* 



12. The cryftals folitary, 



a. Detached, 



b. United at the bafe, 



13. The cryftals in pairi or 3 together. 



a. The bafe of the prifm of each cryftal cohering. 



b. Pearl-like, cohering. 



c. Mutually perforating each other. 



14. Aggregate, Syst. «a/. xii. 3. p. 84. «, 2. f, ^ 

 Aman. acad. I, />. 477. «. 10. tab* \6, f6, 



a. In fcries. * - . , 



b, Fafcicled, 



