Xonotlite



Xonotlite is a calcium silicate hydroxide mineral, related in structure to wollastonite. It has not been re-analyzed since the study of Palache (1935) which gave: SiO2 48.60, CaO 44.64, MnO 0.49, MgO 0.25, H2O 3.97, total = 97.95 wt. %.
Xonotlite was described from Franklin by Bauer and Berman (1935) and Palache (1935), from which this description is largely taken; it has not been studied since, and it has not been found at Sterling Hill. Xonotlite has been mislabeled calciothomsonite.
Xonotlite occurs as colorless acicular crystals, up to 2 cm, which appear white in the aggregate. The crystals form matted white aggregates and radial clusters, some randomly arranged. Crystals forming on clinohedrite may have an epitactic relation, as yet unstudied. The luster is vitreous; the cleavage is parallel to the elongation; and the density is 2.71 g/cm3. The fluorescence in ultraviolet is moderate violet, stronger in shortwave than longwave. Although xonotlite resembles many species, the restricted and diagnostic paragenesis at Franklin, together with its fluorescence, serve to identify it unambiguously. Frondel (1972), on the basis of an unpublished study, has noted that many similar minerals are not present in this assemblage and that crystals fitting the description of xonotlite are indeed that species.
Xonotlite occurs in vugs in a porous recrystallized assemblage consisting predominantly of hancockite, manganaxinite, prehnite, willemite, and garnet, and lesser amounts of roeblingite, clinohedrite, barite, ganophyllite, and numerous other species. This first occurrence was found in 1933 in the north end of the 500 level of the Franklin Mine. This assemblage was recovered in abundance by collectors, and thus is not rare, although fine xonotlite specimens are prized. (Dunn, 1995)


 Location Found: Franklin
     
 
 Year Discovered: 1866
     
 Formula: Ca6(Si6O17)(OH)2
 Essential Elements: Calcium, Hydrogen, Oxygen, Silicon
 All Elements in Formula: Calcium, Hydrogen, Oxygen, Silicon
     
 IMA Status: Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
     
Fluorescent Mineral Properties

 Shortwave UV light: Moderately bright violet
 Mid wave UV light: Violet
 Longwave UV light: Violet
 Additional Information: Phosphoresces moderately bright violet. Fluoresces best at shortwave
     
 To find out more about this mineral at minDat's website, follow this link   Xonotlite

     
 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.450

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.84


The Picking Table References
 PT Issue and PageDescription / Comment
V. 58, No. 1 - Spring 2017, pg. 24Fluorescent Minerals of Franklin and Sterling Hill, N.J., Part 2, Richard C. Bostwick - Xonotlite
View IssueV. 45, No. 1 - Spring 2004, pg. 15The 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 - Xonotlite
View IssueV. 33, No. 2 - Fall 1992, pg. 11The Check List of Franklin-Sterling Hill Fluorescent Minerals - Xonotlite (Fluorescent Info)
View IssueV. 18, No. 2 - September 1977, pg. 22The Fluorescent Minerals of Franklin and Sterling Hill, NJ by Richard C. Bostwick - Xonotlite
     
Images

     
Xonotlite, axinite, willemite, from FranklinXonotlite, axinite, willemite, from Franklin under shortwave UV Light
Xonotlite, axinite, willemite, franklinite (black), and hendricksite mica (brown), from Franklin, New Jersey. From the collection of, and photo by JVF.
Xonotlite, axinite, willemite, from Franklin, New Jersey under shortwave UV light. The xonotlite fluoresces purple, axinite red, willemite green, and the franklinite and hendricksite mica is non-fluorescent. From the collection of, and photo by JVF.


Xonotlite crystals, roeblingite, amethystine clinohedrite, feldspar and hendricksite mica from Franklin, NJXonotlite crystals, roeblingite, amethystine clinohedrite, feldspar and hendricksite mica from Franklin, NJ under shortwave UV Light
Xonotlite crystals (white, tan), roeblingite (white), amethystine clinohedrite (light gray purple tint), feldspar (tan) and hendricksite mica (black) from Franklin, NJ. From the collection of, and photo by Robert A. Boymistruk.
Xonotlite crystals, roeblingite, amethystine clinohedrite, feldspar and hendricksite mica from Franklin, NJ under shortwave UV light. The xonotlite fluoresces violet and gray, roeblingite red, amethystine clinohedrite yellow and feldspar maroon, the hendricksite is non-fluorescent. From the collection of, and photo by Robert A. Boymistruk.







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