168 NATURAL HISTORY. [NORTH 
the paranthine and also the dipyre; substances which* to¬ 
gether with several others provisionally placed in this 
glass Case* stand in need of further investigation as to their 
chemical and crystallographical characters. 
Case 32 contains micaceous and talcose substances. 
Our imperfect knowledge of the optical properties and 
chemical constitution of many varieties of the former* does 
not admit of their being arranged according to those distinc¬ 
tive characters; such varieties as have been more closely 
examined in this respect* may be divided into potassa-mica 
(by far the most common)* which has two axes ; magnesia- 
mica (from Vesuvius* Siberia* and Monroe* in New York)* 
which has but one axis;—and the lithia-mica * which* be¬ 
sides the beautiful peach blossom* red* violet* greenish- 
grey* and white scaly varieties known by the name of lepi - 
dolite * from Rozna in Moravia* likewise comprises several 
large-foliated varieties of what was formerly considered as 
common mica* such as that from Zinnwald in Bohemia and 
Altenberg* accompanied by apatite* tin-stone* and topaz, 
—The species and varieties of the talcose substances are 
likewise very imperfectly understood. Among the speci¬ 
mens of talc in this glass Case may be specified the com¬ 
mon or Venetian (which enters into the composition of cos¬ 
metics), and the indurated talc* to the former of which 
may be referred the green radiated variety from Siberia* 
composed of distinct groups of small diverging laminae* 
and to which the name of pyrophyllite is commonly given; 
— agalmatolite * (Werner’s bildstein* Haiiy’s talc gla- 
phique)* employed by the Chinese for carving Images* 
vessels, &c.;— chlorite , crystallized in aggregated* small* 
modified rhombic prisms; the earthy and foliated varieties, 
coating crystals of octahedral magnetic iron-stone* &c.;— 
pinite , crystallized in regular hexagonal prisms* and gie - 
sec kite, from Greenland* which appears to be a variety of 
this species .—Fahlunite, under which name several dis¬ 
tinct substar res have been noticed by authors. 
Case 33. This and part of the following Case chiefly 
contain substances related to hornblende or amphibolic 
minerals* among which may be specified the basaltic and 
common hornblende, including the pargasite ; —the actino - 
lite or strahlstein (divided by Werner into the glassy* 
common* and fibrous varieties) ; —the grammatite or tremo - 
