BUILDING AND ORNAMENTAL STONES. 351 



tbe SO called verdantique marbles, wliere tlie white veins of ealcite or 

 dolomite lose tlieir polish and crumble away more rapidly than the 

 serpentine composing the balk of the rock. Good exami)le8 of tliis are 

 to be seeu in the bases of the two statues in front ot the City ilai! in 

 Boston. Stones which, like many marbles, contain seams of mica, talc, 

 or other minerals, are objectionable for like reasons. Thus th.' nuirble 

 column supporting the statue of Lincoln in front of the City Ilall at 

 Washington, though having been in place but some twenty years, is to- 

 day cracked from top to bottom, owing to the opening of one of iliese 

 seams of talc. It may be stated further that in the majority^ of marbles 

 and such other stones as are used chiefly for decoration work, those 

 variously colored lines and veins or structural features which give 

 the stone its chief beaiity are in reality flaws and lines ot weakness. 

 There is many a beautiful imported marble which when sawn into a 

 thin slab will scarcely bear its own weight, but must be backed by 

 cheaper and stronger material. 



It may be said here that the essential qualities of a marble, aside from 

 color, which may vary almost indefinitely, are that it shall possess a text- 

 ure sufliciently com})act and hard to take a smooth surface and acquire a 

 high ])olish. The chief defect in nearly all American marbles, and one 

 that does not as yet seem to be fully realized, is that they are too coarsely 

 crystalline. This not only ren.ders the production of a perfect surface 

 diflicult, but the cleavage facets frequently reflect the light fioni below 

 the surface in such a way as to destroy its nniformitj^ Ilowever good 

 the color may be, a stone of this nature must always rank lower than 

 one that is so fine grained as to appear non-crystalline or amorphous. 

 It is this fact, and this alone, that renders the American marbles now 

 in the market inferior to such as are imported from Belgium, the French 

 Pyrenees, Italy, or northern Africa. Those who are seeking new source:; 

 of material will do well to bear this in mind.* 



Time of quarrying. — The seasoji of year during which a stone was 

 quarried may also, in certain cases, be M'orthy of note. It is well known 

 that many stones can be quarried with safety only during the summer 

 season, but Griiber goes a step further and states t that while the best 

 time for quarrying is during the summer, the freshly quarried material 

 should not be allowed to lie in the sun and dry too (pdckly, as it is lia- 

 ble thereby to become shaky. This he regards as particularly likely to 

 liai)pen to sandstone. Stone quarried in winter, or during verj' wet 

 seasons, is liable, according to this authority, to have but slight tenacity 

 when dried, and to remain always particularly susceptible to the eilects 

 of moisture. Finally, he states, a stone is liable to disintegration if 

 built immediately into a wall without seasoning. Stones for carved 

 work are to be quarried in the spring, since such longest retain their 

 quarry water, and this, if once lost, no subsequent wetting can restore. 



"Stone, IiuIianupoli.H, Ind., February, 188'J. 

 Die Buuimiteriiilien-Lchre, p. GL 



