8(58 On Crystallography. 



I. Secondary forms considered with respect io the mod'ifica- 

 t'wns which then/ present of the primitive form, 



TliC crystal is called, 



a. Pyrnniidafcd {pyramidt')^ when the primitive form being 



a prism, has on each of its bases a pyramid which has 

 as many faces as the prism has panes. Example: Py- 

 ramidatcd phosphated lime. 



b, Prismaied {prismc), when the primitive form being com- 



posed of two pyramids joined at their bases, these py- 

 ramids are separated by a prism. Ex. Prismated zir- 

 con, prismaled quartz. 

 Semi'prismafed, when there is only the half of the 

 number of riclges situated around the common base, 

 which are intercepted by panes. Ex. Semi-prismaled 

 S'llphated lead. 



f. Based {base), when, the primitive form being a rhomboid, 



or an assemblage of two pyramids, the summits are 

 intercepted by facets perpendicular to the axis, and 

 performing the function of bases. Ex. Based carbo- 

 nated lime, based sulphur. 



d. Poinfed {epointe), when all the solid angles of the 



primitive form are intercepted by solitary facets, Ex. 

 Pointed mesotvpe. 



We shjill also use the terms hi-pointed {his^porntc) y 



tripointcd (friepoinle), quadripointed {quadricpointe)y 



according as each solid angle may be intercepted by 



. two, three, or four facets. Ex. Tripointed analcime, 



quadripointed sulphurated iron. 



e, Margimited (emargine), when all the ridges of the pri- 



mitive form are each of them intercepted by a facet. 

 Ex. Marginated garnet. 



We shall also use the term li-marginated, iri^ 

 marginated, as each ridge is intercepted by two or 

 three facets. Ex. Trimarginated garnet. 

 f Peri-hexahedral, peri-octahedral, peri-decahedral, peri- 

 dodecahedralf when the primitive form being a prism 

 with four panes, is changed by the effect of decrements 

 into a hfxahedral, octahedral, decahedral, or dodeca- 

 hedral prism We also denominate peri-dodecahedron 

 a crystal the nucleus of which being a regular hexa- 

 hedral prism, has its'six longitudinal ridges intercepted 

 by as many facets. Ex. Peri-hexahedral sulphated 

 copper, peri-dodecahedral emerald. 



g. Recurved (racconrci) , when the primitive form being a 



prism with rhombic bases, the longitudinal ridges con- 

 tiguous 



