12 H. How on Natro-boro-calcite and another Borate. 
while Laurent* describes a salt =5NaO, 24B0,+52HO, and 
Roset one =3CaO, 5BO, when ignited, and it is a little curious 
that the formula given above oe the soda salt corresponding 
to Larderellite and the salt.o 
NaO, me Sat esi 
I mentioned that the = es no “ian of crys- 
talline structure to the n 
I received this poe “Tn spite of your odd formal the 
iitiectty, the form comes out as sharp as possible. The crystals 
are excessively thin translucent tables or plates. They have a 
rhombic outline and the angles pers =80° or more, owing 
than 00118 of an English inch. The lon Speke needles of 
the Tiza are in great contrast to the rod tables of the recent 
mineral in your last letter; of that the plates are about ‘0048 of 
an inch from side to side, but some are a little larger, others a 
little smaller. In some you see regular cleavage, that is, a small 
rhomb chipped out of one side. As far as form goes therefore it 
ease of soda is very cu 
I may state that I had peters SS the opportunity of appre- 
ciating the great accuracy of this description of the appearance 
of the two minerals. 
Arguing from the chemical composition, which however may 
not be quite established, and the crystalline structure, I conceive 
the mineral in question to constitute a new species, and I propose 
for it the name of Cryptomorphite (xguztos, occultus, uoggy, forma) 
in allusion to its microscopic crystalline structure 
The truth of the last sentence in Prof, Robb’s letter is very 
apparent. In my former paper on the subject I adverted to the 
existence of Natro-boro-calcite in the Gypsum here as confirming 
; Liebig und Kopp’s Jahresbericht, 1849, p. 226. 
+ Liebig und Kopp’s Jahrb., 1852, p. 313. 
| 
