j8 The West Ajnefican Scientist. 



WONDERFUL MICA. 

 Mica, although one of the most common of minerals, is also 

 one of the most interesting. Some of its varieties are the first 

 specimens collected by the beginner, while others are often the 

 last to find their way into the cabinet of the mineralogist. Take 

 from the cabinet the mica group and the collection is robbed of' 

 some of its choicest minerals. What other mineral has the per- 

 fect cleavage, and the brilliant polish of mica; and what other 

 mineral will separate into those delicate flexible plates? Mica has 

 truly wonderful qualities. What collection would be complete 

 without the beautiful rose and lilac lepidolites. a mineral found in 

 so few localities, principally Maine, Connecticut and Massachusetts. 

 Lepidolite contains from two to five per cent of the rare earth 

 lithia, that imparts to the blow-pipe flame a deep crimson color. 

 Specimens from Rumford, Maine, are often penetrated with 

 slender cystals of pink tourmaline, while from other local- 

 ities in the State plates of muscovite surrounded by lepidolite 

 are often completely changed to the latter mineral. Associ- 

 ated with lepidolite (in all three states) are those wonderful 

 colored tourmalines that have made the Mt. Mica locality at Paris, 

 Me., so famous. Clevelandite is also found in connection with 

 both, generally the gangue. From Branchville, Conn., comes 

 another curious curved mica, and some of the specimens would 

 resemble a mass of silvery soap bubbles, while in others may be 

 seen the gradual change fi'om the foliated through the curved to 

 the semi-globular. The gangue is often pure while albite, which 

 gives the mica a pleasing background. Spherical mica from 

 Bennington, Vt , is another old form, brilliant balls from one- 

 fourth to one and one-fourth inches m diameter protrude from 

 the granite matrix. The plumosed variety with the scales 

 arranged in plume-like form is a very desirable specimen. At 

 Mineral Hill Delaware Co., Pa., has been found the interesting 

 mineral vermiclite, a mineral belonging to the chlorite group but 

 related to the micas. When heated this mineral will expand forty 

 times its original size. Its color is green, but after heating 

 becomes white. Perhaps the most useful and the only mica that 

 has an economical value is the variety 'muscovite,' from mines in 

 Alstead, N. H.. have been taken sheets four feet across. In 1883 

 a single mass weighing 512 lbs. was also discovered. The best 

 quality is used principally in stove manufactories, while the poor 

 quality, clippings, etc , are ground up to be used as a lubricant 

 for machinery and for fire proof packing. There are numerous 

 mineral substances that owe many of their interesting qualities to 

 some form of mica. Take lor instance the gem stone aventurine 

 quartz, which is simply transparent quartz spangled with scales ot 

 mica. That interesting flexible sandstone (itacolumite). the very 

 gangue of the diamond itself owes much of its flexibility to 

 hydrous mica. — J. y. Alton in the Collectors' Ills. Magazi7ie, 



