COMPOUND MINERALS. 93 



If the rows of individuals, thus arranged, approach so near each 

 other that they at last meet, so as to form a continuous mass, they 

 are said to occur in leaves or membranes ; examples of which are 

 found in Native Gold. 



Compound minerals, like those of membranes, may again join in 

 a new composition, in which the individuals are arranged, for the 

 most part, at right angles to each other. This composition is de- 

 nominated the reticulated shape, and is often seen in Titanite. 



The third division comprehends the stalactitic and coralloidal 

 shapes. The first of these consists of individuals which are per- 

 pendicular to every point of a straight cylindrical or linear support, 

 in its whole circumference. Examples of this composition are com- 

 mon in Carbonate of Lime, in those productions called stalactites : 

 more rarely, in Chalcedony and Iron Pyrites. The coralloidal shapes 

 consist of individuals inclined at an angle to their support, which, 

 although linear, is not straight; they are fixed upon this support in 

 every part of the circumference, exactly as is the case in the sta- 

 lactitic shapes. This kind of imitative shapes is frequently met 

 with in Arragonite. 



. 78. AMORPHOUS COMPOSITION. 



If the mass, formed by the junction of several individu- 

 als, is not only of an irregular shape, but if even in this, we 

 cannot trace any resemblance with the shape of another 

 body, the mineral is said to be massive. 



Massive minerals are amorphous, irregular compositions of individ- 

 uals of the same species, which are in contact with each other on 

 all sides. The difference between massive minerals, and those forms 

 resulting from the groupes of crystals which deviate more or less 

 from the spheroidal shape, consists merely in the strong adhesion of 

 the former to the surrounding masses of other species. It is form- 

 ed, however, and assumes a shape corresponding to its own inherent 

 powers, and does not depend upon its support, inasmuch as we are 

 led to suppose both of them to be of contemporaneous origin. 



Massive minerals, of a smaller size, are also disseminated minerals, 

 which have again been subdivided according to the size of the par- 

 ticles. Very large masses of amorphous minerals sometimes enter 

 into the composition of rocks, as Carbonate of Lime and Gypsum, 



