Heulandite

Object/Artifact

-

Crater Rock Museum

Name/Title

Heulandite

Entry/Object ID

2014.1.52

Description

Chemical Composition: Al(OH)3 Crystal System: Hexagonal System Description: Common Name: Heulandite Chemistry: (Ca, Na)2 - 3Al3(Al, Si)2Si13O36 - 12H2O Group: Silicates Location: Unknown Description: Specimen is hemi-spherical with a void in the center.. Center has a druzy lining with a few distinct crystals also. Physical Charateristics: Color is colorless, white, gray, green, pink, yellow, red, brown and black. • Luster is vitreous to pearly on the most prominent pinacoid face and on cleavage surfaces. • Transparency: Crystals are transparent but most commonly translucent. • Crystal System is monoclinic; 2/m • Crystal Habits include blocky crystals described as diamond-shaped, trapezoidal and old fashioned coffin shape with the two faces of a pinacoid usually prominent. Crystals are often modified by secondary faces with pairs of triangular faces very common. Prismatic and acicular forms are also known and are difficult to identify as heulandite. In aggregate specimens this face can be oriented upward producing a crust of curved pearly faces or it can be oriented to the side where the tops of the crystals jut out like the roof tops of a suburban community. Crystals can be simple or complexly modified by a variety of prism and pinacoid faces. • Cleavage is perfect in one direction parellel to the prominent pinacoid face. • Fracture is uneven. • Hardness is 3.5 - 4, maybe softer on cleavage surfaces. • Specific Gravity is approximately 2.1 - 2.3 (very light due to the open channels and high water content). • Streak is white. • Associated Minerals are extensive and include quartz, calcite, apophyllite, barite, pyrite, prehnite, pollucite, tourmaline, scolecite, analcime, chabazite, ferrierite, mordenite, laumontite, natrolite, stilbite and other zeolites. • Notable Occurrences are wide spread and include Poona and Nasik Districts, India; Iceland; New Jersey; Washington; Boron, California; Patterson, New Jersey; Arizona and Oregon, USA; Nova Scotia and Quebec, Canada; Iran; Sardinia, Italy; Rio Grande do Sul and Goias, Brazil; New South Wales and Phillip Island, Victoria, Australia; New Zealand; Kola Peninsula, Russia; Scotland and Rhone Valley, Switzerland. • Best Field Indicators are crystal habit, density, cleavage, luster and associations. 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

2-3/4 in

Width

1-3/4 in

Length

1-7/8 in

Location

Location

Display Case

FS-11

Room

Frieda Smith Hall

Building

Crater Rock Museum

Category

Permanent

Moved By

Ian Cunningham

Date

December 27, 2023