410 SKY. MINERALS. 



The specimens thus described are almost invariably 

 colourless and transparent, or white ; but occasionally 

 they assume a brown tinge. One specimen occurred of 

 a sea green hue and of perfect transparency; but the 

 flesh colour not uncommon in this mineral was not 

 observed, although found in the other members of this 

 family which are here seen. 



With respect to the exact locality of this substance, I 

 have only found it at Talisker and at Dunvegan, although 

 it is probable that it exists in many other parts of this 

 extensive island, which the labour of years would scarcely 

 suffice to examine with the scrupulosity necessary for this 

 purpose. 



In the spot already quoted between Loch Eynort 

 and Loch Brittle, I also found laumonite, one of the 

 least common of the zeolite family. It is occasionally 

 mixed with stilbite, and appears also to exist in the 

 amygdaloids, in which cases it seems to determine or 

 accelerate their decomposition. But it is also found in 

 large masses on the shore, mixed with irregular crystals 

 of calcareous spar, and containing cavities in which it is 

 crystallized at liberty in distinct and perfect forms. These 

 masses attain to twenty pounds in weight, and though 

 now, while at rest, in a state of apparent integrity, they 

 crumble to pieces on the slightest effort to move them. 

 The weather appears to exert no other action on them, 

 since the mineral possesses its snowy whiteness and bril- 

 liancy equally on the exposed surfaces as in the interior. 

 Their present state offers a singular contrast to their 

 former one ; since they must have been in a far different 

 condition to bear the fall from the high cliffs whence they 

 have been detached, without entire destruction. 



In the same fertile spot to the mineralogist I also found 

 the no less rare substance ichthyophthalmite. It is not 

 abundant, but to compensate this, the crystals are perfect 

 and of great size, presenting two modifications. In the 

 first the square prism is truncated on all the angles, and 



