660 
MINERALOGY: R. A. DALY 
the deposition of the Hmestone mud, which he interprets as likewise a 
chemical precipitate. The calcareous matrix has, in fact, the uniform, 
exceedingly fine grain characteristic of chemically precipitated lime- 
stone, though it encloses fragments of fossil shells and skeletons. 
Triimpy, in the western Rhatikon, found similar albites, new crystal- 
lizations, in Jurassic limestone. These crystals are generally less than 
0.03 mm. long and seldom as much as 0.05 mm. long. They are asso- 
ciated with colorless to somewhat brownish foils of mica with the same 
order of dimensions. Triimpy also describes secondary albite and ortho- 
clase crystals, 0.05 to 0.08 mm. long, in the Tertiary (Flysch) limestones 
of the same district. The feldspars enclose roundish granules of calcite 
identical in size and form with the normal constituents of the mud- 
like limestone. In many cases the feldspar is merely a 'Bindemittel' for 
such grains of calcite. Triimpy agrees with Heim that the feldspars 
grew, 'schwebend,' in the calcareous mud. 
Both Heim and Triimpy found no difficulty in distinguishing these new 
feldspars from the quite different clastic feldspars occasionally seen in 
the same thin sections. They have good evidence that the new feld- 
spars were not developed by dynamic or contact metamorphism of the 
limestones — a conclusion borne out by the extremely fine grain of the 
calcareous material. 
Thirty years before, Kaufmann^ described similar albites, ''doubtless 
formed in situ^\ as occurring in Jurassic, Lower Cretaceous, Upper Cre- 
taceous, and Eocene limestones of the "Emmen- und Schlierengegenden" 
of Switzerland. The maximum length of the albite crystals in any of 
the formations is 0.08 mm. Kaufmann noted that they abound spe- 
cially in the purer limestones. 
Independently Lory"^ had found non-clastic albite and orthoclase crys- 
tals in most of the non-metamorphosed Jurassic limestones of the French 
Alps. Such feldspars are described as particularly abundant in nodu- 
lar and geodic concretions. Pyrite crystals and minute, doubly-termi- 
nated quartz crystals accompany the feldspars. All the crystals are 
explained as growths in limestone muds charged with organic (bitumi- 
nous) matter. A year later Lory^ noted the occurrence of albites and 
bipyramidal quartzes in Eocene limestone at Montricher, near Saint 
Jean-de-Maurienne. He attributed the formation of the feldspars to 
special conditions which were not stated, but he excluded metamor- 
phism as an explanation. He found orthoclase crystals in the cast of 
an Ammonite. 
Foullon^ reported the fine-grained to dense Eocene limestone of the 
Aegean island of Rhodes to contain 1.1 to 1.2% of well crystallized sili- 
