PLATE I. 



Fig. I. — Cliloritc-scliist. Tlie cover-glass of a slide of the rock was re- 

 moved, waslicd with ether, and treated with hot HCl which 

 dissolved away the magnetite, and then the photomicrograph was 

 taken. The ground is a mosaic of albite grains, veiled with 

 irregular membranes of clinochlore. There are a great number 

 of subangular or rounded rliomb-shapcd colorless crystals with 

 high refraction and also strong birefringency. Tlicy are of niinu(e 

 size, have the appearance of leucoxene, and are here identified 

 as either titanite or orthite. They are also present in almost all 

 chlorite-schists elsewiiere, in which they are accompanied with 

 somewhat large yellow granular anhedra, which no doubt belong 

 to epidote. Pp. 7-8. Magnified 90 diameters. 



Fig. 2. — Slaty mica-seliist. The preparation was first digested with HCl 

 which dissolved away the magnetite, and tlie remaining black 

 dust disappeared only after ignition when the slide become clear. 

 There are superabundant needles of rutile, some showing the 

 characteristic knee-shaped twins. Hemimorpliic magnesium-tour- 

 maline is also found among; them as in fio*. 4. P. 6. Mao-nified 



Ö O o 



50 diameters. 



Fig. 3. — Contact -metamorphosed limestone (ophicalcite). Calcite with 

 mosaic structure, enclosing patches of dirty calcite which always 

 embrace slender diopside, the latter now entirely changed into 

 a serpentine. There is besides an antigorite-serpentine into 

 which the calcite-rhombohedrons project with idiomorphie outline. 

 P. 10. Magnified 50 diameters. 



Fig. 4. — Argillite. The dark-gray phyllitic rock was cut to a thin slice, 

 and digested in HCl and ignited, thus entirely removing the 

 graphitoid. Interlarded in lamellar sericite are claysl ate -needles 

 which are small as compaTed with those of slaty mica-schist (fig. 2). 

 Tourmaline is also present. P. 8. Magnified 84 diameters. 



Fig. 5. — Contact-metamorphosed limestone. A six-sided crystal and the 

 grains of diopside as shown in the photomicrograph have been 

 changed for the greater part into fibrous serpentine leaving cores 

 of the intact mineral. We can here trace the various stages of 

 serjientinization from diopside. P. 10. Magnified 50 diameters. 



Fig. 6. — Contact-metamorphosed limestor.e. The small acicular needles of 

 ilvaite are enclosed in calcite-crystals of an early generation ; 

 but the anhedra of diopside in the immediate neighborhood are 

 peculiarly free from the enclosures of ilvaite. Pp. 10-11. 

 Mafjuified 50 diameters. 



