Crystal Description of Scheelite :

Scheelite forms perfect tetragonal dipyramidal crystals that look very much like octahedrons. The crystals may also be truncated with minor pyramids, on the top and/or bottom points of the crystal. Which show Scheelite's true form. Scheelite may also be found in massive and granular form.

Other minerals that form crystals similar to Scheelite include wardite, anatase and powellite. Powellite, CaMoO4, is isostructural with Scheelite which is why it forms similar crystals. The two minerals form a series in which the tungsten of Scheelite is substituted by the molybdenum of Powellite. Powellite fluoresces a yellow color while Scheelite fluoresces a bright blue under short wave ultraviolet light. Of course since molybdenum can substitute for tungsten, some Scheelite specimens will show a yellow fluorescence.

Scheelite crystals can be mistaken as octahedron crystals. So fluorite with it's perfect octahedral cleavage and fluorescence. Can be mistaken for the brownish orange Scheelite. Massive Scheelite has often been mistaken for massive quartz, but then the fluorescence of Scheelite is a dead giveaway.

 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Scheelite Distinguishing Characteristics:

The fluorescence may be confusing especially when it becomes whitish or yellow from molybdenum substitution, but the high gravity differentiates it from fluorescent fluorite, and the crystals are so common that they will often be seen.

Specimens from worldwide localities show little difference in their color of fluorescence. Unlike other minerals, Scheelite is a "self-activated" mineral. Its fluorescence is due to the mineral itself, rather than some chance chemical impurity. The characteristic blue to bluish white fluorescence of this species is a valuable property in prospecting for Scheelite deposits at night. Old mines have even been reopened when mine shafts were examined with ultraviolet lamps.

Scheelite crystals can be mistaken as octahedron crystals. So fluorite with it's perfect octahedral cleavage and fluorescence. Can be mistaken for the brownish orange Scheelite. Massive Scheelite has often been mistaken for massive quartz, but then the fluorescence of Scheelite is a dead giveaway. 

 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Occurrence, Localities and Origins:

Occurs in connection with the tin deposits of Bohemia, Saxony and Cornwall; in quantity in New South Wales and Queensland. Found in the United States at Trumbull, Connecticut; at the Atolia District near Randsburg, San Bernardino County, California; near Mill City Pershing County, Nevada; near Dragoon, Cohise County, Arizona; in Lake County, Colorado; near Gage, New Mexico, where it occurs with pyrite and galena in a vein cutting limestone, and in the placer gravels at Nome, Alaska. High perfection orange scheelite crystals suitable for mineral collectors are being mined in China.

Production. Scheelite has been mined in quantity in Idaho, Alaska, California, Nevada, Arizona, and New Mexico, as a source of tungsten, but most of this element has heretofore been produced from other compounds, mainly wolframite. For some years it was produced in large quantity near Bishop, Inyo Co., California.

Scheelite is a subordinate ore of tungsten, with wolframite furnishing the greater amount on a worldwide basis. In the US, Scheelite has been the more important source of the metal. Tungsten is used principally in the manufacture of tool steel, various steel alloys and electric furnaces. It is also employed as the filaments in electric-light bulbs, in the manufacture of sodium tungstate which is used for fireproofing cloth, as a mordant in dyeing, and for a number of other minor purposes.

 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Composition, Structure and Associated Minerals:

Scheelite is found in granite pegmatites, contact metamorphic deposits, and high temperature veins. In these veins, it occurs usually with quartz in crystalline rocks associated with cassiterite, topaz, fluorite, apatite, molybdenite, wolframite, and many other metallic compounds. Found at times with gold. As a contact metamorphic product in altered limestone intruded by granite it is associated with typical scarn minerals like garnet and epidote. It is probably in all cases deposited from hot solutions. Sometimes found as crystals, but usually occurs reniform, with a columnar structure; also massive and granular.

Identification and Diagnostics

Scheelite is distinguished from limestone, which its massive forms closely resemble, by its higher specific gravity and the absence of effervescence with HCl. From quartz it is distinguished by its softness and from barite by greater hardness and higher specific gravity. Nearly all scheelite fluoresces under short wave ultra violet light. This can make for a fast method of finding scheelite specimens.



 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

If any test fails to meet the requirement, that test shall be repeated twice. The results of both retests shall meet the requirement. Specimen for retesting may be taken from the original test sample or from a new test sample. For chemical analysis, retests need only be for those specific elements that failed to meet their test requirement. If the results of one or both retests fail to meet the requirement, the material under test shall be considered as not meeting the requirements of this specification for that classification.

In the event that, during preparation or after completion of any test, it is clearly determined that prescribed or proper procedures are not followed in preparing the test specimen, or in conducting the tests, the test shall be considered invalid, without regard to whether the test is actually completed, or whether the test results meet, or fails to meet the requirement. That test shall be repeated, following proper prescribed procedures. In this case, the requirement for doubling the number of test specimen does not apply.



 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Chemical Analysis

Chemical analysis shall be performed on specimen of the electrode being classified. Any analytical technique may be used but, in cases of dispute, reference shall be made to established published methods. The referee method shall be ASTM F288. The results of the analysis shall meet the requirements of Table 1 for the classification of electrode under test.

Acceptance

Acceptance of the electrodes shall be in accordance with the provisions of AWS A5.01M:A5.01 (ISO 14344 MOD). 



 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

The following are several points on specification for tungsten and oxide dispersed tungsten electrodes for arc welding and cutting normative references:

1. Classification of a tungsten electrode is based on its chemical composition.

2. The tungsten and oxide dispersed tungsten electrodes covered by this specification are classified using a system that is independent of the U.S. Customary Units and the International System of Units (SI). Classification is according to the chemical composition of the electrode as specified in Table 1.See Clause B7 for classification descriptions.

3. Electrodes classified under one classification shall not be classified under any other classification in this specification.

4. No electrode meeting the requirements of any other classification shall be classified under EWG.

5. The electrodes classified under this specification are intended for gas tungsten arc welding (GTAW), as tungsten arc cutting(GTAC), plasma arc welding (PAW), or plasma arc cutting (PAC), but that is not to prohibit their use with any other process for which they are found suitable.



 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies.

1. The following AWS standard (AWS standards are published by the American Welding Society, 550N.W.LeJeune Road, Miami, FL 33126) is referenced in the mandatory sections of this document:

AWS A5.01M/A5.01 (ISO 14344 MOD), Procurement Guidelines for Consumables – Welding and Allied Processes – Flux and Gas Shielded Electrical Welding Processes

2. The following ANSI standard (The ANSI standard is published by American Welding Society, 550N.W.LeJeune Road, Miami, FL 33126) is referenced in the mandatory sections of this document:

ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes

3. The following ASTM standards (ASTM standards are published by the American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428 - 2959) are referenced in the mandatory sections of this document:

ASTM E 29, Standard Practice for using Significant Digits in Test Data to Determine Conformance with Specifications

ASTM F 288, Standard Specification for Tungsten Wire for Electron Devices and Lamps

4. The following ISO standard (ISO standards are published by the International Organization for Standardization) is referenced in the mandatory sections of this document:

ISO 31 – 0:1922, Quantities and Units – Part 0: General principles; and Annex B, Rule A

 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

This standard specifies requirements for classification of non-consumable tungsten electrodes for inert gas shielded arc welding, and for plasma welding, cutting, and thermal spraying.

This specification makes use of International System of Units (SI) and the U.S. Customary Unites. The measurements are not exact equivalents; therefore, each system must be used independently of the other without combining in any way when referring to material properties. The specification designated A5.12M uses SI Units; and the specification designated A5.12 uses U.S. Customary Units. The later units are shown within brackets or in appropriate columns in tables and figures. Standard dimensions based on either system may be used for sizing of tungsten electrodes or packaging or both under A5.12M or A5.12 specification.



 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn