340 GIESECKfe ON THE MINERALOGY OF DISKO. 



2. Stilbite, — in thin hexagonal tables. 



b. In quadrangular prisms, acuminated by truncated 

 pyramids. 



3. Chabasie, — crystallised in the primitive rhomb. 



b. In truncated rhombs. 



c. In macles. 



4. Analcime, — crystallised in the form of leucite. 



5. Compact Zeolite, white and red. — This mineral occurs in 

 cavities and veins in all the rocks of the Floetz-Trap-formation, 

 except the basalt-tufF. 



6. Apophyllite or Ichthyophthalme, occurs — 



a. In prisms perfectly rectangular. 



b. Also with the solid angles replaced. This variety was 



mistaken for mesotype and described as Mesotype 

 epointe. 



c. By a curious arrangement of the particles, the crystals 



of apophyllite at the extremities present the shape of 

 a barrel.* They also occur acuminated and diverging 

 sometimes in the form of a rose. In perfect cubes, 

 the apophyllite occurs in Greenland only in the basalt- 

 tufF, accompanied with delicate capillary mesotype. 

 Notwithstanding, in Faroe and Iceland it is found in 

 wacke. This substance forms an opaque jelly in nitric 

 acid, frothing up and exfoliating. The apophyllite 

 also occurs in a radiated form similar to stilbite, but 

 with a more brilliant lustre, presenting on the surface 

 a crystallisation similar to the cock's-comb barytes. 



8. Carbonate of Lime occurs in all rock of this formation, in 

 cavities and veins, of a greyish- white colour, sometimes massive, 

 sometimes crystallised in rhombs, also in pyramids of three and 

 six planes, and in prisms of six planes. I have found it also 

 crystallised in nearly perfect cubes. 



9. Igloite, the arragonite of Haiiy, and hard calcareous spar of 

 Bournon, occurs fibrous, radiated, and crystallised in pyramids of 

 three planes ; also in prisms of six planes, terminating by degrees 

 in pyramids. 



10. Radiated and concentric globular mineral, of a yellowish- 

 green colour, which I take to be Wavellite. , 



11. Compact quartZy bacillairej and crystallised in prisms, in 

 geodes. 



12. Calcedony, massive, and very rarely in cubes. Quartz and 

 calcedony occur in all the rocks. 



13. Opal, common, in veins and cavities, white and yellow, 

 particularly in basalt. 



14. Cereolite, a mineral of a yellowish, brownish, and greenish 

 colour, very similar to compact lithomarge. 



* The cylindrical apophyllite, according to the experiments of Dr. Brews- 

 ter who examined some specimens which I transmitted to him, differs in a 

 remarkable manner from the apophyllite of Iceland, Faroe, Uto, and Fassa. 

 Its optical properties he has found to be of a very curious kind. 



