194 THE HOLY LAND. 
CHAP, its matrix^, not only the same alternate convex 
V. '' 
« — , — and concave fractures which sometimes charac- 
terize the horizontal fissures of basaltic pillars*, 
but also the concentric layers which denote 
concretionary formation'. It is hardly possible 
to have a more striking proof of coincidence, 
resulting from similarity of structure in two 
substances, otherwise remarkably distinguished 
from each other*. 
(1) Je Jis une remurque a celte occasion; c'est que ces gemmes, qui 
deviennent si dures, etoient singulierement friahlts au sortir de leurs 
gites: plusieurs gros prismes se hriserenl entre mes mains." Hist. Nat^ 
des 3Ii?i. torn. II. p. 32. It is the same with the common jdint, which, 
when first taken from a bed of chalk, sometimes breaks in the hanr}, 
and is penetrated with visible moisture. This also is the case with 
regard to the Hungarian opals : the workmen often expose them to 
the sun, before they venture to remove them. 
(2) 11 offre un accident remarquable, et que j'ai observ^ le premier 
dans ces gemmes; c'est que ses extr^mit^s, au lieu d'etre planes, ont 
uue saillie arrondieco mme les basaltes articules. Get accident se 
rencontre ^galement dans les ^meraudes ct les aigues marines de la 
m^me montagne. J'en ai des exemplaires de toutes les nuances qui 
oflFrent ces articulations, soit en relief, soit en creux." Hist. Nat. 
des Min. torn. \\. p. 28. 
(3) " J'en ai plusieurs echantillons, ou Ton volt, quand on les 
regarde contre le jour par une de leurs extremit^s, des hexagones con- 
centriques, qu'on distingue quelquefoisjusque vers le centre du prisme: 
ces hexagones sont formes par les lames qui ne sont appliqu^es suc- 
cessivement a ch:\cune de ces faces." Ibid. torn. II. p. 31. 
(4) The mineralogical reader may add to this a remarkable fact, 
recently communicated to the author by the Rev. James Lambert, of 
' Trinity College, Cambridge. The radiating pillars upon the coast of 
St. Andrew's in Scotland, bearing the name of the Spindle Rock, ate 
nothing more than a spheroidal mass, which once occupied an orbi- 
cular cavity, after the manner in which zeolite is exhibited in porous 
aggregates : the prisms diverge from a common centre like the 
acicular 
