Muscovite, Mica, Isinglass
SpiritRock Shop
Click on any photo to see a larger version
Museum Specimens
Official PayPal Seal
Return to Main Minerals List
Muscovite is a silicate mineral that contains potassium and aluminum. It is also
known as Mica or Isinglass. Muscovite may form in layers of sheets (called
“Books”) which are clear with a pearly luster on cleavage faces or as a rock
forming mineral found in igneous, metamorphic and sedimentary rocks, often
having a flakey, sparkly look.

Muscovite typically occurs in metamorphic rocks, particularly gneiss and schist,
where it forms crystals and plates. It also occurs in igneous rocks such as
granites and fine-grained sedimentary rocks. Large crystals of muscovite are
often found in veins and in pegmatite.

The name “Muscovite” comes from the term “Muscovy-glass”, a name formerly
given to the mineral because it was actually used in Russia for windows.

Muscovite reflects light strongly from broken fragments. This is caused by a
natural cleavage resulting in thin sheets (“Basal Cleavage”). Sheets naturally
form in alternating layers, resulting in Muscovites distinctive shape. When the
sheet growth is unobstructed they form hexagonal sheets. A unique variety in
Brazil forms yellow five pointed stars and is called "Star Muscovite".

Muscovite is usually clear but may be silvery, coppery silver, light gray, brown,
pale green, or rose-red in color depending on the thickness of the sample and
presence of impurities.
The Mica Group

Large crystals of mica used for various applications are typically mined from granitic pegmatites. Collectible Mica  
specimens in the USA can be found in Spruce Pine, Franklin-Sylva and Shelby Hickory districts of North Carolina.

The mica group of sheet silicate (phyllosilicate) minerals includes several closely related materials having nearly
perfect basal cleavage. Mica is normally found to be monoclinic (pseudo hexagonal), there also are hexagonal,
orthorhombic, and triclinic forms generally referred to as polytopes. Among the principal rock-forming minerals,
micas are found in all three major rock varieties; igneous, sedimentary, and metamorphic.

Of the 28 known species of the mica group, only 6 are common rock-forming minerals.
1) Muscovite, (Potassium Mica) the common light-colored mica.  It was originally called “Muscovy glass” because it
came from the Muscovy province of Russia
2) Biotite, (Magnesium Iron Mica) which is typically black or nearly so, is the most abundant. Biotite was named for
Jean-Baptiste Biot, a 19th-century French physicist who studied the optical properties of micas.
3) Phlogopite, (Magnesium Mica) typically brown. Its name comes from the Greek word ‘phlogopos’ for fire like,
which was chosen because of the reddish glow (color and luster) of some specimens
4) Paragonite, (Sodium Mica) which is macroscopically indistinguishable from muscovite, also is fairly common.
From the Greek word ‘paragon’  “to mislead,” was so named because it was originally mistaken as talc.
5) Lepidolite, (Lithium Mica) generally pinkish to lilac in color, occurs in lithium-bearing pegmatites. From the Greek
word 'lepidos' meaning “scale,” was based on the appearance of the mineral’s cleavage plates
6) Glauconite, (Iron Potassium Phyllosilicate Mica) a green species that does not have the same general
macroscopic characteristics as the other micas, occurs sporadically in many marine sedimentary sequences. All of
these micas except Glauconite exhibit easily observable perfect cleavage into flexible sheets. Glauconite, which most
often occurs as pellet like grains, has no apparent cleavage. Although typically green, was named for the Greek word
for blue ‘glaucos ‘

Muscovite is the most common type of Mica.  Whenever the word mica is used, it is normally understood to mean
muscovite. Mica is also known as Cat-gold, Cat-silver, Glimmer, Glist, Katen-silber, Katzen-silber, Katzengold, Or
Des Chats, and Rhomboidal Mica.

Mica is found to occur in book form in pegmatites intruding mica schists. The presence or absence of orthoclase
feldspar indicates the chances of finding mica in the pegmatite. Mica forms at the expense of orthoclase feldspar.
The presence of tourmaline crystals and decomposed feldspar in the pegmatites is a great indication of the possible
formation of high quantity of mica.

Mica pegmatites have been found to occur in various shapes and sizes mostly occurring as lenses. They may occur
as veins or in massive form. It is difficult to know when the vein will play out making the mining of mica highly
speculative and risky. The sudden change of surrounding minerals resulting in total disappearance of mica from the
working area is common.

A rare crystallized Mica that can be found near Shelby, Cleveland County, North Carolina is a 6 sided Phlogopite
Mica.  It has sharp, well defined mica crystals and most specimens have a red-brown clay in the crevices between the
crystals. The mica crystals are brown, platy hexagonal form, with secondary edge faces. When back lit or viewed in
the correct sunlight angle the crystals show translucent solidification of the mica plates. These are highly sought after
North Carolina crystallized Mica specimens!
Crystalized Mica, Shelby, NC
Tourmaline and Mica in Feldspar
Purple (Lepidolite) Mica framed Silver Mica natural
specimen from the Lapa Mine, Aracuai, Minas Gerais,
Brazil. We procured this from a crystals and  mineral
importer based out of Atlanta, Georgia We were able
to hand select the best specimens they had.

This specimen weighs 3.2 oz (91g)
and measures 4 x 2.1 x 0.34 inches (103 x 55 x 8.6mm)
Item # 24PFSMICA05161050
Purple framed Silver Mica Book from Brazil

$20.00
Purple (Lepidolite) Mica framed Silver Mica natural
specimen from the Lapa Mine, Aracuai, Minas Gerais,
Brazil. We procured this from a crystals and  mineral
importer based out of Atlanta, Georgia We were able
to hand select the best specimens they had.

This specimen weighs 2.8 oz (82g)
and measures 3.4 x 2.2 x 0.43 inches (88 x 57 x 11mm)
Item # 25PFSMICA05162050
Purple framed Silver Mica Book from Brazil

$19.00
Purple (Lepidolite) Mica framed Silver Mica natural
specimen from the Lapa Mine, Aracuai, Minas Gerais,
Brazil. We procured this from a crystals and  mineral
importer based out of Atlanta, Georgia We were able
to hand select the best specimens they had.

This specimen weighs 1.9 oz (55g)
and measures 3.6 x 1.9 x 0.22 inches (93 x 49 x 5.8mm)
Item # 26PFSMICA05163050
Purple framed Silver Mica Book from Brazil

$17.00
Purple (Lepidolite) Mica framed Silver Mica natural
specimen from the Lapa Mine, Aracuai, Minas Gerais,
Brazil. We procured this from a crystals and  mineral
importer based out of Atlanta, Georgia We were able
to hand select the best specimens they had.

This specimen weighs 1.5 oz (45g)
and measures 3.5 x 1.9 x 0.19 inches (90 x 49 x 5mm)
Item # 27PFSMICA05164050
Purple framed Silver Mica Book from Brazil

$14.00
Item # MIC706169922
Phlogopite Mica from
North Carolina
$49.00
This brown Magnesium Mica specimen (phlogopite) has multiple layered crystals. This
specimen is from Franklin, Macon County, North Carolina. Large mica crystals like this
are perfect for specimen collectors. This piece will peel off many very thin mica sheets.
Specimen weighs 10.1oz or 0.63 lb (289g)
and measures 5.5 x 3 x 0.66" (13.9 x 7.8 x 1.68 cm)
Item # 8MIC06168781
Phlogopite Mica from
North Carolina

$39.00
This brown Magnesium Mica specimen (phlogopite) has multiple layered crystals with
attached clear quartz. This specimen is from the Spruce Pine District in Mitchell County
North Carolina Appalachian Mountains. Large mica specimens like this are perfect for
collectors. This piece will peel off many very thin mica sheets.
Specimen weighs 5.9oz or 0.37 lb (170g)
and measures 3.7 x 2.4 x 0.95" (9.5 x 6.1 x 2.4 cm)
Item # 9MIC06168232
Tourmaline in
Phlogopite Mica from
North Carolina

$49.00
This brown Magnesium Mica specimen (phlogopite) has multiple layered crystals with
attached green Tourmalines and white quartz. This specimen is from the Spruce Pine
District in Mitchell County North Carolina Appalachian Mountains. This is a very special
collection piece.
Specimen weighs 6.3oz or 0.39 lb (181g)
and measures 3.9 x 2 x 0.97" (10 x 5.2 x 2.47 cm)
Item # 10MIC06164433
BlackTourmaline on  
Phlogopite Mica from
North Carolina

$68.00
This Magnesium Mica specimen (phlogopite) has a mica book (25 x 19 x 8mm) and a
second large mica window covered with black Tourmalines (Schorl) in pegmatite matrix.
This specimen is from the Spruce Pine District in Mitchell County North Carolina
Appalachian Mountains. This is a very special large cabinet collection piece.
Specimen weighs 36.5oz or 2.28 lb (1037g)
and measures 5 x 3.9 x 3.1" (12.8 x 9.9 x 7.9 cm)
Item # MIC03178942
Clear Mica Blades from Nica,
Mexico

$49.00
This Potassium Mica Blade specimen (Muscovite) from Nica, Mexico. This specimen from our
personal collection was procured in the early 1970's in Arizona.
Specimen weighs 15oz 0.94 lb (426g) and measures 5 x 2.6 x 2.2" (12.8 x 6.6 x 5.7cm)
Item # 13MIC06164750
Clear Mica from
Ellensburg Depot NY

$26.00
This Potassium Mica specimen (Muscovite) is a nice Natural Mica window.  This
specimen was procured from a mineral dealer in New York in 2010
Specimen weighs 0.44oz or 0.16 lb  (74g)
and measures 4.4 x 1.7 x 0.53" (11.3 x 4.3 x 1.35 cm)
Item # 14MIC06164402
BlackTourmaline on  
Phlogopite Mica from North
Carolina
$42.00
This Magnesium Mica specimen (phlogopite) has a mica book covered with black Tourmalines
(Schorl) in pegmatite matrix. This specimen is from the Spruce Pine District in Mitchell County
North Carolina Appalachian Mountains. This is a very unique cabinet collection piece.
Specimen weighs 5.8oz or 0.36 lb (165g) and measures 4.1 x 2.3 x 0.86" (10.5 x 5.8 x 2.19 cm)
Item # 15MIC06164502
Large Book of
Phlogopite Mica on
Pegmatite from N.C.

$39.00
This Magnesium Mica specimen (phlogopite) has a thick mica book on pegmatite
matrix. This specimen is from the Spruce Pine District in Mitchell County North Carolina
Appalachian Mountains. This is a very nice cabinet collection piece.
Specimen weighs 9oz or 0.56 lb (256g)
and measures 4 x 2.5 x 1.8" (10.3 x 6.4 x 4.6 cm)
Item # 16MIC06169471
Large Book of Mica  
from Maine
$35.00
This is a rare mica specimen from the White Mountains in the Northeastern Appalachian
Mountains of Maine. This is a great cabinet collection piece with thick compressed
layers of Mica.
Specimen weighs 3.6oz or 0.22 lb (103g)
and measures 4.1 x 1.7 x 0.59" (10.4 x 4.3 x 1.51 cm)
Item # 17MIC06161571
Large Book of Mica  
from Maine

$34.00
This is a rare mica specimen from the White Mountains in the Northeastern Appalachian
Mountains of Maine. This is a great cabinet collection piece with thick compressed
layers of Mica.
Specimen weighs 2.9oz or 0.18 lb (83.5g) and measures 4 x 1.6 x 0.45" (10.1 x 4.2 x 1.16 cm)
Item # 30MIC07165992
Very Rare Mica Books from the
Old Pressley Sapphire Mine in
Canton, North Carolina

$99.00
This is a very rare specimen with thick mica books in feldspar matrix.  Thick mica
books are quite rare. Located in Haywood County, near Canton, the Pressley
Sapphire Mine is one of the oldest operating mines in western North Carolina.
Made famous by the discovery of the 1445 carat "Star of the Carolinas" Star
Sapphire.  Corundum, Sapphires and many other precious minerals for rock
collectors are still being found at this mine. About 16 years ago the mine was
taken over by George McCannon and is currently operated under the name of the
“Old Pressley Sapphire Mine”

Large Cabinet Specimen weighs 26.5oz or 1.65 lbs (752g)
and measures 5.4 x 3.4 x 2.4" (13.7 x 8.7 x 6.2 cm)
There are 2 large and thick mica books on this piece.
They are 1.5" (38.9mm) and 1.2" (30.9mm) thick
Item # 31MIC07165912
Very Rare Mica Books from the
Old Pressley Sapphire Mine in
Canton, North Carolina

$95.00
This is a very rare specimen with thick mica books in feldspar matrix.  Thick mica
books are quite rare. Located in Haywood County, near Canton, the Pressley
Sapphire Mine is one of the oldest operating mines in western North Carolina.
Made famous by the discovery of the 1445 carat "Star of the Carolinas" Star
Sapphire.  Corundum, Sapphires and many other precious minerals for rock
collectors are still being found at this mine. About 16 years ago the mine was
taken over by George McCannon and is currently operated under the name of the
“Old Pressley Sapphire Mine”

Large Cabinet Specimen weighs 25.2oz or 1.57 lbs (716g)
and measures 6 x 4 x 1.7" (15.4 x 10.1 x 4.3 cm)
There are 2 large and thick mica books on this piece.
They are 1.9" (49.9mm) and 1.9" (48.8mm) thick. The largest book is "stepped"
This is an extra-large cabinet specimen of
Feldspar and Quartz matrix with brown Mica
(Muscovite) and large green beryl crystals. This
piece is from an old collection we acquired and
was in a box marked from the Ray Mine in
Burnsville, Yancey County, North Carolina. This
is a beautiful specimen from a great location.

This specimen weighs 106 oz or 6.63 lbs (3010g)
and measures 7.9 x 5.3 x 3.3 inches (20.1 x 13.5 x 8.5 cm)
One Beryl Crystal is 2.4 x 0.56" (63 x 14.4mm)
the second is @ 1" x 1" (27 x 27mm)
Item # 32MICB07165943
Muscovite and Beryl Crystals
from Yancey County, NC

$74.00
This is an extra-large cabinet specimen of
Feldspar and Quartz matrix with brown Mica
(Muscovite) and green beryl crystals. This piece
is from an old collection we acquired and was
in a box marked from the Ray Mine in
Burnsville, Yancey County, North Carolina. This
is a beautiful specimen from a great location.


This specimen weighs 74 oz or 4.68 lbs (2120g)
and measures 7.4 x 4.8 x 2.89 inches (19 x 12.2 x 7.3 cm)
Item # 33MICB07165942
Muscovite and Beryl Crystals
from Yancey County, NC

$56.00