Name/Title
MicroclineEntry/Object ID
2009.62.129DDescription
Chemical Composition: Potassium aluminum silica
Crystal System: Monoclinic System
Description: Common Name: Microcline
Chemistry: KAlSi3 O8 , Potassium aluminum silicate.
Group: Feldspars
Location: Crystal Peak, CO
Description: Small specimen with distinct flat planes in two sections. Color is primarily flesh and blue-green.
PHYSICAL CHARACTERISTICS:
Color is usually off-white,yellowish, flesh pink, brown or green.
Luster is vitreous to sometimes pearly or dull if weathered.
Transparency crystals are translucent, but usually translucent to opaque.
Crystal System is triclinic; bar 1
Crystal Habits include blocky, or tabular crystals. Crystals have a nearly rectangular or square cross-section with slightly slanted dome and pinacoid terminations. Twinning is common. Crystals can be twinned according to the Albite, Pericline, Carlsbad, Manebach and Baveno laws. Microcline can be found as a major rock forming component in granites, syenites and in metamorphic gneisses.
Cleavage is perfect in one and good in another direction forming nearly right angled prisms.
Fracture is conchoidal.
Hardness is 6 - 6.5.
Specific Gravity is approximately 2.5 (average)
Streak is white.
Associated Minerals are quartz, muscovite and plagioclase feldspars.
Other Characteristics: Lamellar twinning may cause a grooved effect on cystal and cleavage surfaces that appear as striations. Perthite intergrowths causes a stripped appearance is some specimens.
Best Field Indicators are occurence, twinning, color and luster.
Fracture: Conchoidal
Hardness: 6 Orthoclase
Luster: Vitreous
Occurrence: Microcline is a polymorph of other minerals that share the same chemistry but have different crystal structures. If positive identification can not be made by field methods then the specimen may be refered to as a potassium feldspar or K-spar. The other k-spar minerals are sanidine, orthoclase and anorthoclase. The differences between these minerals are minor in hand samples but microcline tends to be deeper colored, is usually striated on cleavage planes and is the only one that can be, but is not always, a deep green (amazonite).
Rock Type: Sedimentary
Specific Gravity: 2.5
Streak: whiteCollection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Width
1-1/4 inDepth
1 inLength
2 inWeight
0.14 ozLocation
Location
Display Case
DS-2Room
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Curtis GardnerDate
May 18, 2023Notes
Added current location while cleaning shelfLocation
Drawer
MiddleShelf
Middle, MiddleWall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Scott LonganDate
September 26, 2009Location
Container
LeftDrawer
Top ShelfShelf
RightCabinet
Case #39Wall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
Permanent