Tremolite



Tremolite is a calcium magnesium silicate hydroxide mineral of the amphibole group. Unpublished analyses by [Dunn] indicate that tremolite can contain up to 5 wt. % MnO and 6 wt. % ZnO, in material with 2 wt. % FeO. There exists in local specimens a complete solid solution series from end-member tremolite, through actinolite, to ferroactinolite containing barely 52 mole % of the endmember.
Tremolite is a common mineral in the Franklin Marble, occurring with other silicates in aggregates and as isolated crystals. Tremolite has been little studied locally. Nuttall (1822) noted it originally and Palache (1935) provided some data; otherwise the extant study is that of Klein and Ito (1968), from which these data were taken.
Tremolite occurs as euhedral crystals in much of the Franklin Marble; some are rounded, and some are up to 10 cm in length. Tremolite is colorless to white or gray, with vitreous luster, normal amphibole prismatic cleavages, and a density of approximately 3.1 g/cm3. In ultraviolet, much tremolite from the Franklin Marble fluoresces light blue in shortwave; some specimens fluoresce light yellow in longwave. Dorling and Zussman (1984) found a zincian tremolite with asbestiform habit to have abundant Wadsley defects and multiple twinning; they also observed fibrils with a triple-chain structure.
Tremolite is found as euhedral crystals and mixed with other accessory minerals in much of the Franklin Marble. It has been found in many of the local quarries and rarely in the calcium silicate units of the orebody; actinolite is more common in the Franklin orebody, especially in proximity to the franklinite ores. The tremolite studied by Klein and Ito (1968; #4) was associated with rhodochrosite and calcite in a vein in franklinite-calcite ore in which the tremolite is separated from the ore by carbonates. Frondel (1972) has reported tremolite as one of the white fibrous amphiboles found, alone and sometimes mixed with zincite, on slickensides; this intimate mixture with zincite is known locally as calcozincite (Shepard, 1876). Much serpentine also may be found in this material, together with other fibrous minerals.
In the marble, fine crystals, 10 cm and more in length, have been found associated with graphite, chondrodite, calcite, arsenopyrite, phlogopite, chlorite, and a large number of other species. Such tremolite crystals are occasionally warped and fractured, and some broken ones are "healed" by other minerals. They may contain inclusions of other minerals. Amphiboles in the marble were studied by Germine (1986).
At Sterling Hill, tremolite was found in an asbestiform habit on slickensides in the 1680 stope, just below the 1400 level. (Dunn, 1995)


 Location Found: Franklin and Ogdensburg
     
 
 Year Discovered: 1789
     
 Formula: ☐{Ca2}{Mg5}(Si8O22)(OH)2
 Essential Elements: Calcium, Hydrogen, Magnesium, Oxygen, Silicon
 All Elements in Formula: Calcium, Hydrogen, Magnesium, Oxygen, Silicon
     
 IMA Status: Approved
     
Fluorescent Mineral Properties

 Shortwave UV light: Fairly bright pale blue
 Mid wave UV light: Weak yellow
 Longwave UV light: Weak yellow
     
 To find out more about this mineral at minDat's website, follow this link   Tremolite

     
 References:
Dunn, Pete J. (1995). Franklin and Sterling Hill New Jersey: the world's most magnificent mineral deposits. Franklin, NJ.: The Franklin-Ogdensburg Mineralogical Society. p.459

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.81


The Picking Table References
 PT Issue and PageDescription / Comment
V. 58, No. 1 - Spring 2017, pg. 20Fluorescent Minerals of Franklin and Sterling Hill, N.J., Part 2, Richard C. Bostwick - Tremolite
View IssueV. 45, No. 1 - Spring 2004, pg. 14The Art of Fluorescent Mineral Photography, With Special Attention to the Minerals of Franklin and Sterling Hill Photographing the More Popular Franklin and Sterling Hill Fluorescent Minerals - Tremolite
View IssueV. 33, No. 2 - Fall 1992, pg. 11The Check List of Franklin-Sterling Hill Fluorescent Minerals - Tremolite (Fluorescent Info)
View IssueV. 27 No. 2 - Fall 1986, pg. 10Minerals of the Franklin Quarry, Philip P. Betancourt, Tremolite
View IssueV. 18, No. 2 - September 1977, pg. 20The Fluorescent Minerals of Franklin and Sterling Hill, NJ by Richard C. Bostwick - Tremolite
View IssueV. 13, No. 2 - August 1972, pg. 13The Fluorescent Minerals of Franklin/Ogdensburg Area by Frank Z. Edwards - Tremolite (Fluorescent Info)
View IssueV. 7, No. 2 - August 1966, pg. 14The Minerals of Sterling Hill 1962-65 by Frank Z. Edwards - Tremolite (small article)
     
Images

     
Tremolite crystal sprays in franklin marble from the Franklin Quarry Franklin, NJTremolite crystal sprays in franklin marble from the Franklin Quarry Franklin, NJ under shortwave UV Light
Tremolite crystal sprays (gray) in franklin marble from the Franklin Quarry Franklin, NJ. Photo by JVF.
Tremolite crystal sprays in franklin marble from the Franklin Quarry Franklin, NJ under shortwave UV light. The tremolite fluoresces bright blue-white and the marble is non-fluorescent. Photo by JVF.







All content including, but not limited to, mineral images, maps, graphics, and text on the Franklin-Ogdensburg Mineralogical Society, Inc. (FOMS) website is licensed under a
Creative Commons Attribution-NonCommercial 4.0 International License.
Creative Commons License