The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1880-04-24
MICA.


merly applied to a great variety of
rocks much resembling each other,
then supposed to be identical but
with increased facilities for mineral
investigation, by chemical and optical
methods not then known, the name
is now applied to a less numerous but
extensive class of mineral, the pecu-
liar character of which ia their easy
splitting into thin, elastic plates, or
lamiLse. This is due to cleavage, a
property possessed by nearly all crys-
talline bodies, that of breaking in
certain planes, which are called
cleavage planes and which bear a
relation to the axes OF crystals. Mica
Is remarkable for the ease with which
1t separates, AMI to all sedementary
rocks into which it enters as q con-
stItuent it imparts more or less Of this |
property. 1t is to this cleavage prop |
erty, and TO the fact of its iniusibility |
by moderate heat, that mica is SO |
largely used for stoves, in which it is /
used for doors and the eye holes for
blast furnaces, as il stops out the
air and enables the inside 10 be |
seen. It Is also used for optical
purposes, and extensively Tor mount
ing minute objects, being exceeding
tough and transparent Ia thin plates.
It's also notwithstanding to the micro
scepist, 90 it frequently contains crys-
tails Of other minerals imbedded IN Ii.
some of which, with polarized light,
are objects of wonderful beauty and
scientific interest. It would be i'm
possible to particularize the various !
kinds of minerals found as inclusions :
q mica; magnetic, limsnite and
gothite, in arborescent forms, caused |
Oy iron minerals, in their protean ,
shapes, are deemed the most attract ,
i've. But quartz is found II q variety
Of initiative forms of much interest {
to the miueIa!ogist. This popularity {
IF mica is q great advantage 70 IN ,
most minerals have to be {
lplit or reduced into thin sections by Z
he lapidary, by grinding and polish t
ngr before they can be submitted to 2
examination by polar !
zsd light. But in the micas, and in Z
ONE micacious rocks, they appear &
D be almost ready for use, so delicate i
nd easy Is the cleavage. q
Mica Is chemically a silicete of a
lamins and potash, with some iron, 81
lagneSia ard soda. 1t is usually b
y1Tated, that is, a little water is u
resent The ",ougheued glass" pro- f
uced by art 10 recent times was long a
.nce !.uad in mica, which is re- ?
l2rkEhe for its toughness and elias D
city. Crystals OF a very large size 5,
re found IL some countries, notably N
; Pennsylvania. The potash mica q
NuscOTiie; it is found in tae south. Il
II and western parts O! Utah 10 n
nall plates, slightly colored by dem "
rites Of lion. BIotits IS generally al
s. dark co,o-. II forms the black II
.!ca CT cur beautiful temple granite, cr
here it Is associated with horn n
lende and other, minerals. Lepido. #
lelaue is also a black mica. PHO d
optic Is generally brown or red. L o.
a mice frequently foGHd IL lime. 81
ones. Lepidoite is Z red Or pink h
lIca, containiBg the rare earth
thla. Mica scBists are slate, OF N
,hi3to5a LOCKS, in Ehich some kind n,
mica forms the principalingredienl. m
-iCa slates are more Or less cleave- re
Die, by reason Of the presence of y
inute flakes Of mics. Mica is fire. "
lently colored red or yellow, from b
tide of iron, and there are instances re
its being mistaken fer gold. Near 5.
,uth Cottonwood and Union Fort 81
is kind OF mica Is found in the m
nds. Mica ground ia a mill forms M
loose, light mass OF scales, some ar
Ga: resembling bran. Sand of this tb
I'd is found at Skull Valley; when an
is is subjected to proper washing, adj
e four-ike particles form useful fo,
gment. Mica powder ia useful III In,
e arts for many purpCses-for fire. de
of paints, also as an absorbent of an
tro-glycerine, its elastic nature pre- tn
ming accidental explosions by per- dit
ssion, without interfering with the rir
ergies when exploded by q full Ia,
mate, or the usual devices. ma
MicaCeous rocks are abundant in mr.
.ah, in the Gallons of the Wasstch 40
ST of Sessions, and other csnons of dii
r settlements north of this city to
e groupings of this important e,
neral ara found. fri
When it is considered bow impor M
1t and numerous are lis uses it will Al,
well to make efforts through the On
,ritory to obtain it in useful crystals hi,
-ge enough for the purposes here wi
or for mineral fire proof Tt
int. Mica IS one Of the constit. an
nts OF q true granite; quartz is fir
other. This mineral has been al at,
ldy described in these columns; as al.
dspar is also one of the ingredients r,
granite, and as it is also useful in So
e arts, it will be described in the tw
.ure notices of the minerals and va
2ks of Utah. of
For special desriptions Of minerals III
g class books sold in this city will =,
re the young student a competent 81
.men!ary knowledge of miueralogy.
Is by handling minerals and rocks, N
led by such a work, and noticing 90
e form, color, cleavage, weight, e,
and other physical proper
IS, that an extended knowledge of
inera!s is acquired.