427 



Clinopyramid ; elinoprism ; elinodome See Pyramid, Prism, and Dome 



respectively. 



Clinorhombic See Monoclinic. 



Compact Applied to very fine-grained rocks in which the individual particles 

 are too minute to be seen by the naked eye. 



Conehoidal (Ger. muschelig) Having the shape of a shell ; applied to the 

 concave and convex fracture of some rocks and minerals, as, for instance, 

 obsidian and flint. 



Concretionary Applied to a rock-structure in which certain constituents 

 have been so aggregated as to form nodules or irregular lumps. 



Cone-in-COne Structure (Ger. Tuten, Nagel) A curious concretionary structure 

 found in marls, limestones, and coals, and characterized by a concentric, 

 conical arrangement of the rock material. 



Conformity (Ger. concordante Auflagerung) A term applied in strati- 

 graphy to an uninterrupted sequence of beds having the same dip and 

 strike. 



Contact-metamorphism (Fr. metamorphisme de juxtaposition)' A term 

 applied to the alteration of the surrounding rocks produced by the intrusion 

 of igneous rocks (exomorphic metamorpUtm). Some geologists also in- 

 clude, under contact-metamorphism, the effect produced on the intrusive 

 rock (endoniorphic metamorphism) . 



Contemporaneous Of the same age (synchronous) ; a term used in petrography 

 to designate interbedded igneous rocks and segregation veins. 



Corroded A term often used in petrography to imply the destructive action 

 of the molten magma of a rock upon the first-formed, or included, crystals. 



Corrugated -Wrinkled, crumpled ; applied to foliated rocks ; also to shrinkage- 

 surfaces. 

 Coulee (Ger. Strom) The French word for a lava-flow or stream. 



Crenitic The name given by Sterry Hunt to his hypothesis of the origin of 

 crystalline schists by the action of springs bringing up mineral matter in 

 solution from below. 



CryptOClastlC An epithet applied by Naumann to clastic rocks whose 

 fragments are of microscopic dimensions. 



Cryptocrystalline A term applied to rocks which are made up of minute 

 crystalline particles. Under crossed nicols sections of such rocks show 

 aggregate polarization, but the individual granules are too small for 

 mineralogical determination. 



CryptOgranitique (Fr.) See Microgranitic. 



CryptomerOUS A term used, synonymously with adeloyene, for finely granular 

 See Phaneromerous. 



Crystalline (Fr. cristallin ; Ger. krystallinisch) This term is used by crys- 

 tallographers to connote the physical properties of crystallized matter, and 

 is applied to any body or portion of a body possessing those properties 

 without regard to its form. By petrographers, on the other hand, the 

 same word is used to denote mineral aggregates which consist of crystal- 

 lized substances, whether in the form of perfect crystals or merely as 

 grains possessing the physical properties of crystals. To remove this 

 difficulty, J. Lehmaim (Entstehung der altkryst. Schiefergest. 1884, 

 p. 257) has suggested the introduction of the word crystaliic (Ger. 

 krystaltisch), to replace crystalline in the former of the two meanings 

 given above. See Holocrystalline, Hypocrystalline, &c. 



