Name/Title
LaumontiteEntry/Object ID
2009.62.17Description
Chemical Composition: CaAl2Si4O12-4H2O
Crystal System: Monoclinic System
Description: Common Name: Laumontite
Chemistry: CaAl2Si4O12-4H2O
Group: Zeolite
Location: Wipple Quarry, Drain, Oregon USA
Description: Very brittle, not metalic, spine like crystals.
PHYSICAL CHARACTERISTICS:
Color is colorless or white and tinted pink, gray, almond yellow or brown.
Luster is vitreous to dull on exposure to light.
Transparency: crystals are transparent to translucent and opaque with exposure to light.
Crystal System is monoclinic; 2 or m
Crystal Habits include nearly square prisms terminated by the flat, slanted face of a pinacoid. also massive, fibrous and radiating. Some good penetration twins are found.
Cleavage is perfect in two directions, forming splinters.
Fracture is uneven.
Hardness is less than 4
Specific Gravity is approximately 2.2+ (very light)
Streak is white.
Other Characteristics: crystals are commonly grooved or striated, and cleavage surfaces have a pearly luster.
Associated Minerals are quartz, calcite, apophyllite, babingtonite, heulandite, natrolite and other zeolites.
Best Field Indicators are crystal habit, luster, density, alteration, and associations.
Fracture: uneven
Hardness: 3 Calcite
Luster: Vitreous
Occurrence: It is found in hydrothermal deposits left in calcareous rocks, often formed as a result of secondary mineralization. Host rock types include basalt, andesite, metamorphic rocks and granites.
Rock Type: Sedimentary
Specific Gravity: 2.2
Streak: White
Texture: crystaline
Variety: Laumontite is a mineral, one of the zeolite groupa hydrated calcium-aluminium silicate. Potassium or sodium may substitute for the calcium but only in very small amounts.
It is monoclinic, space group C2/m. It forms prismatic crystals with a diamond-shaped cross-section and an angled termination. When pure, the color is colorless or white. Impurities may color it orange, brownish, gray, yellowish, pink, or reddish. It has perfect cleavage on [010] and [110] and its fracture is conchoidal. It is very brittle. The Mohs scale hardness is 3.5-4. It has a vitreous luster and a white streak
Laumontite easily dehydrates when stored in a low humidity environment. When freshly collected, if it has not already been exposed to the environment, it can be translucent or transparent. Over a period of hours to days the loss of water turns it opaque white. In the past, this variety has been called leonhardite, though this is not a valid mineral species. The dehydrated laumontite is very friable, often falling into a powder at the slightest touch.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Width
4 inDepth
2-1/2 inLength
4 inWeight
1.08 ozDimension Notes
Dimension taken at widest pointsLocation
Location
Shelf
CS-D-2Room
Curation StorageBuilding
Crater Rock MuseumCategory
PermanentMoved By
Curtis GardnerDate
May 24, 2023Notes
Added current location