Powellite Value, Price, and Jewelry Information

view gemstone encyclopedia

Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons

An overview on Powellite Jewelry and Gems. Covers details and essential information on the physical properties and characteristics of Powellite gemstones.

Powellite Information

Data Value
Name Powellite
Crystallography Tetragonal; crystals usually pyramidal (faces often striated), also tabular; massive, foliated, pulvurent, ocherous.
Refractive Index 1.967-1.985
Colors Straw yellow, greenish yellow, pale greenish blue, blue, blackish blue, dirty white (grayish) to gray, brown, blackish.
Luster Subadamantine to greasy (on fracture surfaces).
Fracture Luster Greasy.
Hardness 3.5-4
Wearability Poor
Fracture Uneven
Specific Gravity 4.23 (varies with tungsten content); Indian material 4.26 (colorless) to 4.28 (brown).
Birefringence 0.011
Cleavage Indistinct
Dispersion 0.058
Stone Sizes The Michigan material is cuttable only to yield extremely minute stones, and until the Indian material was found powellite was essentially unknown as a gem material. The Indian crystals are quite transparent and cuttable, and gems up to about 3 carats have been cut. These are among the rarest of collector gems.
Luminescence Fluoresces yellowish white-golden yellow in both LW and SW.
Luminescence Present Yes
Luminescence Type Fluorescent, UV-Long, UV-Short
Transparency Transparent to translucent.
Absorption Spectrum Not diagnostic.
Formula Ca(Mo,W)O4. Isostructural with Scheelite.
Pleochroism Blue material is blue/green (Michigan); yellow material is yellow/light yellow (India).
Optics o = 1.967-1.974; e = 1.978-1.985. Uniaxial (+).
Optic Sign Uniaxial +

Optics: o= 1.967-1.974; e = 1.978-1.985.

Uniaxial (+).

Occurrence: A secondary mineral in the oxidation zone of ore deposits.

Houghton County, Michigan: blue cuttable material.

Utah; Nevada; California; Arizona; New Mexico.

Pandulena Hill, Nasik, India: unique occurrence, scattered crystals associated with zeolite minerals in basalt cavities.

Turkey; Russia; Morocco.

Name: After the American explorer and geologist, John Wesley Powell.

Ready to learn how to identify gems on your own?

Join our mailing list below to download a FREE gem ID checklist tutorial. See what’s inside…

• Discover the 17 practical steps to gemstone identification (even if you’re just getting started with gemology)

• Learn how you can use specific tools to gather data, make observations & arrive at an accurate ID

• Explore a range of gemological tests… not only will you get familiar with the process but also time-saving shortcuts!