Name/Title
Quartz / MuscoviteEntry/Object ID
2009.62.63Description
Chemical Composition: see description
Crystal System: Orthorhombic System
Description: Common Name: Quartz / Muscovite
Chemistry: SiO2 , Silicon dioxide / KAl2(AlSi3O10)(F, OH)2, Potassium aluminum silicate hydroxide fluoride.
Group:Silicates
Location: Minas Geris, Brazil
Desription: A large translucent hexagonal crystal with a slender elongated crystal ajoining it, in two seperate matrixs, one with a mica structure and one with a maze look , dirty pink in color.
PHYSICAL CHARACTERISTICS OF QUARTZ:
Color is as variable as the spectrum, but clear quartz is by far the most common color followed by white or cloudy (milky quartz). Purple (Amethyst), pink (Rose Quartz), gray or brown to black (Smoky Quartz) are also common. Cryptocrystalline varieties can be multicolored.
Luster is glassy to vitreous as crystals, while cryptocrystalline forms are usually waxy to dull but can be vitreous.
Transparency: Crystals are transparent to translucent, cryptocrystalline forms can be translucent or opaque.
Crystal System is trigonal; 3 2.
Crystal Habits are again widely variable but the most common habit is hexagonal prisms terminated with a six sided pyramid (actually two rhombohedrons). Three of the six sides of the pyramid may dominate causing the pyramid to be or look three sided. Left and right handed crystals are possible and identifiable only if minor trigonal pyramidal faces are present. Druse forms (crystal lined rock with just the pyramids showing) are also common. Massive forms can be just about any type but common forms include botryoidal, globular, stalactitic, crusts of agate such as lining the interior of a geode and many many more.
Cleavage is very weak in three directions (rhombohedral).
Fracture is conchoidal.
Hardness is 7, less in cryptocrystalline forms.
Specific Gravity is 2.65 or less if cryptocrystalline. (average)
Streak is white.
Other Characteristics: Striations on prism faces run perpendicular to C axis, piezoelectric (see tourmaline) and index of refraction is 1.55.
Associated Minerals are numerous and varied but here are some of the more classic associations of quartz (although any list of associated minerals of quartz is only a partial list): amazonite a variety of microcline, tourmalines especially elbaite, wolframite, pyrite, rutile, zeolites, fluorite, calcite, gold, muscovite, topaz, beryl, hematite and spodumene.
Best Field Indicators are first the fact that it is very common (always assume transparent clear crystals may be quartz), crystal habit, hardness, striations, good conchoidal fracture and lack of good cleavage.
PHYSICAL CHARACTERISTICS: Muscovite
Color is white, silver, yellow, green and brown.
Luster is vitreous to pearly.
Transparency crystals are transparent to translucent.
Crystal System is monoclinic; 2/m
Crystal Habits include tabular crystals with a prominant pinacoid termination. Muscovites four prism faces form diamond shaped "books" and if modified by another pinacoid they form pseudo-hexagonal crystal "books". The sides of the crystal often tend to tapper. Also as lamellar rock forming masses and small flakes in detrital matterial. Twinned crystals can form flat five pointed stars.
Cleavage is perfect in one direction producing thin sheets or flakes.
Fracture is not readily observed due to cleavage but is uneven.
Hardness is 2 - 2.5.
Specific Gravity is approximately 2.8 (average)
Streak is white.
Associated Minerals are quartz, feldspars, beryl and tourmalines.
Other Characteristics: cleavage sheets are flexible and elastic, meaning they can be bent and will flex back to original shape.
Best Field Indicators are crystal habit, cleavage, elastic sheets, color and associations.
Fracture: conchoidal
Hardness: 3 Calcite
Luster: Vitreous
Occurrence: Quartz occurs in hydrothermal veins as gangue along with ore minerals. Large crystals of quartz are found in pegmatites. Well-formed crystals may reach several meters in length and weigh hundreds of kilograms.
Muscovite is a common rock forming mineral and is found in igneous, metamorphic and detrital sedimentary rocks.
Rock Type: Sedimentary
Specific Gravity: 2.2
Streak: white
Variety: Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar and comes in a rainbow of colors.
Muscovite is the most common mica, found in granites, pegmatites, gneisses, and schists, and as a contact metamorphic rock or as a secondary mineral resulting from the alteration of topaz, feldspar, kyanite, etc. In pegmatites, it is often found in immense sheets that are commercially valuable.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Height
2 inWidth
2-3/4 inLength
6-1/2 inWeight
21.58 ozDimension Notes
Dimension taken at widest pointsLocation
Location
Wall
NorthBuilding
Storage (old gift shop upstairs)Category
PermanentMoved By
Rawley WyattDate
May 21, 2014Location
Wall
NorthBuilding
Delmar Smith Hall case #47Category
PermanentMoved By
Rawley WyattDate
May 21, 2014Location
Container
LeftDrawer
3rd ShelfShelf
Center, CenterWall
South wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Steve MillerDate
January 14, 2010Location
Shelf
middle left, middle leftWall
south wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Josh E.Date
September 19, 2009Location
Room
Cultural History StorageBuilding
Crater Rock MuseumCategory
Permanent