CUSPIDINE



Cuspidine is a calcium silicate fluoride mineral. Microprobe analyses of Franklin cuspidine yielded SiO2 32.3, 32.8; CaO 63.5, 61.1; F 9.8, 9.5; less 0 = F 4.1, 4.0; total 101.5, 99.4 weight percent and conform closely to the ideal composition. Substitution of (OH) for F is apparently minimal. Additionally, these analyses are in reasonably good agreement with that of Warren.
Cuspidine was originally reported from Franklin by Palache (1910, 1935), as a result of his interpretation of an 1899 analysis by C. H. Warren of colorless crystals associated with nasonite. Samples of this material, unknown for most of the 20th century, were rediscovered by [Dunn], and a brief description was included in a paper on glaucochroite by Leavens et al. (1987). Cuspidine has not been found at Sterling Hill.
Cuspidine occurs as colorless, clear, 2-5 mm distorted crystals with no discernible forms. The density is between 2.965 and 2.989 (Palache, 1910). Franklin cuspidine is readily recognized by its moderately-strong, yellow fluorescence in longwave ultraviolet. Very small crystals may not be discernibly fluorescent. The fluorescence in short-wavelength ultraviolet is similar, but weaker.
Franklin cuspidine occurs in an apparently uncommon assemblage of hardystonite, clinohedrite, nasonite, andradite, and euhedral crystals of glaucochroite. It is in apparent chemical equilibrium with glaucochroite and with hardystonite, which is altered in some specimens to clinohedrite. Cuspidine also occurs within assemblages of glaucochroite crystals as a late-stage phase, forming druses with clinohedrite in solution vugs in willemite. It is rare at Franklin.
The best samples are in the collections at Yale and Harvard Universities, the American Museum of Natural History, and the Smithsonian Institution. (Dunn, 1995)

 Location Found: Franklin
     
 
 Year Discovered: 1876
     
 Formula: Ca4(Si2O7)(F,OH)2
 Essential Elements: Calcium, Fluorine, Oxygen, Silicon
 All Elements in Formula: Calcium, Fluorine, Hydrogen, Oxygen, Silicon
     
 IMA Status: Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
     
Fluorescent Mineral Properties
 Shortwave UV light: Bright orange-yellow
 Mid wave UV light: Violet tint
 Longwave UV light: Weak orange-yellow
 Additional Information: Brief orange-red phosphorescence
     
 To find out more about this mineral at minDat's website, follow this link   Cuspidine

     
 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.409

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.52
The Picking Table References
 PT Issue and PageDescription / Comment
V. 64, No. 1 – Spring 2023, pg. 25Cuspidine—Associations and Notable Finds Through the Years, Chris Luzier
View IssueV. 57, No. 2 - Fall 2016, pg. 15Fluorescent Minerals of Franklin and Sterling Hill, N.J., Part 1, Richard C. Bostwick - Cuspidine
View IssueV. 45, No. 1 - Spring 2004, pg. 10The 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 - Cuspidine
View IssueV. 43, No. 1 - Spring 2002, pg. 16Yellow-Fluorescing Fluorite And Cuspidine From the Franklin Mine, Franklin, New Jersey John Cianciulli, Curator
View IssueV. 40, Combined Issue 1999, pg. 33A Brief Announcement of New Finds of Cuspidine From Franklin, NJ. (small article)
View IssueV. 33, No. 2 - Fall 1992, pg. 10The Check List of Franklin-Sterling Hill Fluorescent Minerals - Cuspidine (Fluorescent Info)
View IssueV. 28, No. 1 - Spring 1987, pg. 3From the Laboratory, Dr. Pete J. Dunn, John L. Baum, Cuspidine
     
Images
     
Cuspidine, calcite, willemite, and franklinite from Franklin, NJCuspidine, calcite, willemite, and franklinite from Franklin, NJ under longwave UV Light
Cuspidine, calcite, willemite, and franklinite from Franklin, NJ. 2 1/4" x 1 1/2". From the collection of Alex & Gary Kerstanski, photo by Alex Kerstanski.
Cuspidine, calcite, willemite, and franklinite from Franklin, NJ under longwave UV light. The cuspidine fluoresces weak light orange, calcite very weak red-orange, willemite green and the franklinite is non-fluorescent. 2 1/4" x 1 1/2". From the collection of Alex & Gary Kerstanski, photo by Alex Kerstanski.
Cuspidine, calcite, willemite, and franklinite from Franklin, NJ under midwave UV LightCuspidine, calcite, willemite, and franklinite from Franklin, NJ under shortwave UV Light
Cuspidine, calcite, willemite, and franklinite from Franklin, NJ under mid-wave UV light. The cuspidine fluoresces light violet to pink, calcite weak red-orange, willemite green and the franklinite is non-fluorescent. 2 1/4" x 1 1/2". From the collection of Alex & Gary Kerstanski, photo by Alex Kerstanski.
Cuspidine, calcite, willemite, and franklinite from Franklin, NJ under shortwave UV light. The cuspidine fluoresces weak orange-yellow, calcite red-orange, willemite green and the franklinite is non-fluorescent. 2 1/4" x 1 1/2". From the collection of Alex & Gary Kerstanski, photo by Alex Kerstanski.






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