Tourmaline

Object/Artifact

-

Crater Rock Museum

Name/Title

Tourmaline

Entry/Object ID

78.62.198

Description

Chemical Composition: NaFe3B3Al3(Al3Si6O27)(OH) Crystal System: Hexagonal System Description: Common Name: Tourmaline Chemistry:NaFe3B3Al3(Al3Si6O27)(OH)4 Class: Silicates Location: Massachusettes Description: Tourmaline (Aluminum Silicate of hexagonal crystalization containing boron) in a matrix of green, black and grey crystaline. The spider-like grey and black Tourmaline crystals are distributed throughout the matrix. PHYSICAL CHARACTERISTICS :Tourmaline is extremely varied in color. Colors include black, brown, green, red, pink, blue, and gray. White, colorless, yellow, orange, and purple colors are less common. Crystals are frequently multicolored, containing two or more distinct colors. Some specimens are pleochroic. Streak White Hardness 7 - 7.5 Crystal System Hexagonal 3D Crystal Atlas (Click for animated model) Prismatic with Triangular Cross Section Prismatic with Pyramidal Termination Crystal Forms and Aggregates Usually as elongated prismatic crystals that are heavily striated. Also as short, stubby, prismatic crystals. Most Tourmaline crystals have a rounded, triangular cross-section. Seldom in tabular crystals. Aggregates include columnar, radiating, botryoidal, stalactitic, in dense groups of tiny, elongated needles, and in compact masses. Transparency Transparent to opaque Specific Gravity 2.9 - 3.3 Luster Vitreous. Some black and brown specimens may be dull. Cleavage 3,2 Fracture Conchoidal to uneven Tenacity Brittle Other ID Marks 1) Strongly pyroelectric. 2) Piezoelectric. 3) A few forms of Tourmaline fluoresce yellow in shortwave ultraviolet light. In Group Silicates; Cyclosilicates; Tourmaline Group Striking Features Color, crystal form, hardness, and deep vertical striations. Environment Elbaite, Schorl, and Liddicoatite are almost exclusively from granite pegmatites, while Dravite and Uvite or mostly from metamorphic environments such as marbles. Buergerite is from igneous rhyolite deposits. Rock Type Igneous, Metamorphic Popularity (1-4) 1 Prevalence (1-3) 2 Demand (1-3) 1 Tourmaline ON EBAY - See more at: http://www.minerals.net/mineral/tourmaline.aspx#sthash.Fi2qzeq4.dpuf Fracture: Uneven to Conhoidal Hardness: 7 Quartz Luster: Glassy Rock Type: Igneous Specific Gravity: 3.0-3.3 Streak: White

Collection

Delmar Smith Mineral Collection

Acquisition

Accession

78.62

Source or Donor

Delmar Smith Mineral Collection

Acquisition Method

Donation

Dimensions

Width

4 in

Depth

1-3/4 in

Length

3-1/4 in

Dimension Notes

Dimension taken at widest points

Location

Location

Shelf

CS-E-2

Room

Curation Storage

Building

Crater Rock Museum

Category

Storage

Moved By

Jillian Mather Kettley

Date

March 5, 2024