Labradorite

Object/Artifact

-

Crater Rock Museum

Name/Title

Labradorite

Entry/Object ID

2014.1.31

Description

Chemical Composition: Al(OH)3 Crystal System: Hexagonal System Description: Common Name: Labradorite Chemistry: Ca(50-70%) Na(50-30%) (Al, Si)AlSi2 O8 Group: Silicates Location: Labrador, New Foundland, Canada Description: Small thick slab with irridescents throughout. (blue, green yellows and oranges.) Physical Charateristics: •Color is gray to smoky black. •Luster is dull to vitreous. •Transparency crystals are transparent to translucent. •Crystal System is triclinic; bar 1 •Crystal Habits include blocky crystals that rarely form free of the host rock and therefore do not usually show their full crystal forms. In sliced sections of rock, the labradorite appears as blocky chunks with a predominance of near right angled corners. Twinning is common and pervasive so that in labradorite it produces a layered or stacked effect. The twin layers are typically only fractions of millimeters to several millimeters thick. Crystals of labradorite are found imbedded in gabbros and other mafic igneous rocks of low silica content. In anorthosites, labradorite is a main constituent. •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 2.70 - 2.74 (average) •Streak is white. •Associated Minerals are biotite, pyroxene and hornblende. •Other Characteristics: index of refraction is 1.55 - 1.75. Play of colors called labradorescence seen from certain directions can cause flashes of blue, violet and green and sometimes orange and yellow. •Notable Occurrences include Labrador, Canada and Scandinavian Peninsula. •Best Field Indicators are occurrence, twinning striations and labradorescence. - See more at: http://www.galleries.com/labradorite#sthash.mDdisUsW.dpuf Hardness: 7 Quartz Rock Type: Sedimentary

Collection

RAGM Mineral Collection

Acquisition

Accession

2014.1

Source or Donor

Crater Rock Museum (unknown donors)

Acquisition Method

Gift

Dimensions

Height

2-1/4 in

Width

1/2 in

Length

2-1/4 in

Location

Location

Display Case

FS-3

Room

Frieda Smith Hall

Building

Crater Rock Museum

Date

January 5, 2024

Location

* Untyped Location

RD-5

Category

Permanent