BUSTAMITE

Bustamite is a calcium manganese silicate of the pyroxenoid group. Calcium and manganese are ordered, and there is a partial solid solution toward both wollastonite and rhodonite. The compositions of Franklin bustamites lie within the known compositional ranges for the species (Deer et al., 1978). The coexistence of bustamite and wollastonite was noted by Mason (1975) who studied a critical Franklin sample, found by John Baum, which contained the minimum MnSiO₃ component required for stability of the bustamite structure. Bustamite is the high-temperature form of CaMnSi₂O₆; the inversion to johannsenite takes place at 830° C, but may be sluggish (Deer et al., 1978).
The relations to wollastonite and rhodonite, well documented in the literature, are supported by these data. Sterling Hill bustamites have higher Mg contents than Franklin material, in keeping with the generally higher magnesium content of Sterling Hill silicates.
Bustamite was reported from Franklin by Larsen and Shannon (1922a); it was separately reported and analyzed by Lewis and Bauer (1922), but they assumed it to be a variety of rhodonite. The keatingine of Shepard (1876) was discredited as bustamite by Palache (1935), but specimens so-labeled in Shepard's collection at the Smithsonian Institution were examined by [Dunn] and found to be rhodonite, as noted by Kemp (1893a). Some bustamite was known informally as manganese wollastonite. A second report of bustamite by Larsen and Shannon (1922b) was subsequently shown by Dunn and Leavens (1986) to be marsturite epitactic on rhodonite.
A detailed and superb study of Franklin bustamite and its relations to rhodonite and wollastonite was given by Hey (1929). Sundius (1931), and Mason (1975) have also studied local material and, together with Ohashi and Finger (1978), have studied the relations among these species. The crystal structure of bustamite was determined by Peacor and Buerger (1962), and the unit-cell and relationship to wollastonite was reinterpreted by Peacor and Prewitt (1963). Viswanathan and Hameit (1986) included Franklin bustamites in their study of lattice expansion and ionic substitutions. Bustamite is known from both Franklin and Sterling Hill.
Bustamite occurs as subhedral crystals, up to at least 8 cm; they are not mentioned in Palache's monograph (1935) and have not been measured. Bustamite varies in color; most Franklin material is light pink to pinkish orange. The color may fade on exposure to light, and weathered surfaces may darken, presumably by oxidation of Mn. Sterling Hill bustamite is sparse and brownish orange. Bustamite cleavages are pinacoidal; three are good, and one is fair. The numerous cleavages give an apparent fibrosity to some cleavage fragments. The luster is vitreous, and the density is 3.30 g/cm³. Some bright pink Franklin bustamite has a moderate-to-dull red fluorescence in longwave ultraviolet, and some specimens are cathodoluminescent, but the intensity of these effects is not proportional to Mn:Ca ratios. Bustamite may be confused with light-colored rhodonite or pyroxmangite; it is differentiated from both by its negative optic sign and from rhodonite by its indices of refraction.
Bustamite is moderately common at Franklin and relatively rare at Sterling Hill. Franklin bustamite occurs in a variety of assemblages, associated with calcite, vesuvianite, rhodonite, wollastonite, garnet, diopside, willemite, tephroite, glaucochroite, johannsenite, margarosanite, clinohedrite, and numerous other species. Only a few of the most notable occurrences are mentioned here.
The initial description of Franklin material by Larsen and Shannon (1922a) was of pink prismatic crystals, up to 1 cm, associated with blue vesuvianite, garnet, mica, and white hyalophane. The intergrowth of these species is very colorful and esthetic. Perhaps selective retention of this material by miners and collectors was practiced; much material has been preserved.
A bright light-pink bustamite in massive platy aggregates to 10 cm occurs associated with hardystonite and willemite at Franklin; some specimens have coronal rims of tephroite and/or hardystonite with a symplectite-like texture. This is the assemblage studied by Hey (1929). This bustamite is also notable for its unique fluorescence in ultraviolet as noted above.
Subhedral to euhedral crystals, light pinkish orange and up to 5 cm in length, occur with calcite, andradite, mica, and traces of willemite at Franklin. Some crystals are slightly resorbed. Little is known of the assemblage.
Of significance are two assemblages with substantial ZnO: the first, intimately associated with green microcline, has the maximum ZnO reported in any bustamite and has no exsolution. The second assemblage, with less ZnO, consists of orange-pink Franklin bustamite occurring in large masses, some weighing kilograms. Willemite is commonly associated; in specimens where willemite is clearly exsolved, as plates and/or as rod-like crystals, lesser amounts of a dark red sodic johannsenite is also exsolved as platy crystals. The material was locally abundant.
Aside from these assemblages for which many specimens exist, there are other, rarer assemblages which deserve mention. These are:
a) Franklin bustamite noted by Leavens et al. (1987) associated with glaucochroite, andradite, and willemite.
b) Franklin bustamite with willemite, in a reactive contact with spessartine; the reaction products are gahnite and tephroite.
c) Franklin bustamite in a coarse-grained, slightly layered assemblage of hardystonite, calcite, and andradite. Minor apatite and clinohedrite are present.
At Sterling Hill, bustamite occurs with tephroite, andradite, calcite, and a dark brown unanalyzed clinopyroxene. It is also found associated with diopside and calcite. (Dunn, 1995)

Location Found:

Franklin (Type Locality) and Ogdensburg

Year Discovered:

1922

Formula:

CaMn²⁺(Si₂O₆)

Essential Elements:

Calcium, Manganese, Oxygen, Silicon

All Elements in Formula:

Calcium, Manganese, Oxygen, Silicon

IMA Status:

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"

Fluorescent Mineral Properties

Shortwave UV light:

Very rarely bright cherry-red

Longwave UV light:

Weak red, rarely bright cherry-red

Additional Information:

Sterling Hill non-fluorescent, Franklin mostly non-fluorescent

To find out more about this mineral at minDat's website, follow this link Bustamite

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.437

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.47

The Picking Table References

	PT Issue and Page	Description / Comment
	V. 64, No. 2 - Fall 2023, pg. 8	Shortwave-Fluorescing Bustamite From Franklin, New Jersey, in a Wollastonite Assemblage James Van Fleet
	V. 64, No. 2 - Fall 2023, pg. 14	Margarosanite Replacing Bustamite From Franklin, New Jersey, Earl R. Verbeek
View Issue	V. 57, No. 2 - Fall 2016, pg. 14	Fluorescent Minerals of Franklin and Sterling Hill, N.J., Part 1, Richard C. Bostwick - Bustamite
View Issue	V. 45, No. 1 - Spring 2004, pg. 9	The 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 - Bustamite
View Issue	V. 33, No. 2 - Fall 1992, pg. 10	The Check List of Franklin-Sterling Hill Fluorescent Minerals - Bustamite (Fluorescent Info)
View Issue	V. 30, No. 1 - Spring 1989, pg. 17	Research Reports, Bustamite & Rhodonite
View Issue	V. 18, No. 1 - March 1977, pg. 20	The Fluorescent Minerals of Franklin and Sterling Hill, NJ by Richard C. Bostwick - Bustamite
View Issue	V. 9, No. 1 - February 1968, pg. 7	Mineralogical Data - Johannsenite/Bustamite
View Issue	V. 6, No. 1 - February 1965, pg. 9	Bustamite
View Issue	V. 6, No. 1 - February 1965, pg. 10	Bustamite and Johannsenite

Images


Bustamite (pink), hardystonite (gray to white), with minor willemite, franklinite (black) and clinohedrite, from Franklin, NJ. From the collection of, and photo by Robert A. Boymistruk.		Bustamite, hardystonite, with minor willemite, franklinite and clinohedrite, from Franklin, NJ under shortwave UV light. The bustamite fluoresces cherry red, hardystonite (blue and lavender), clinohedrite (orange) and the willemite green, the franklinite is non-fluorescent. From the collection of, and photo by Robert A. Boymistruk.


Bustamite (pink), andradite garnet (straw to dark brown) and minor willemite from Franklin, NJ. 3 1/2" x 2 1/4". From the collection of, and photo by WP.		Bustamite, andradite garnet and minor willemite from Franklin, NJ under longwave UV light. The bustamite fluoresces red and willemite green, the andradite garnet is non-fluorescent. 3 1/2" x 2 1/4". From the collection of, and photo by WP.

Bustamite, andradite garnet and minor willemite from Franklin, NJ under shortwave UV light. The bustamite scarcely fluoresces red and willemite green, the andradite garnet is non-fluorescent. 3 1/2" x 2 1/4". From the collection of, and photo by WP


Bustamite (pink), willemite (motor oil green to light green) and minor franklinite (black), from Franklin, NJ. 4" x 3 1/4". From the collection of, and photo by Robert A. Boymistruk.		Bustamite, willemite and minor franklinite, from Franklin, NJ under longwave UV light. The bustamite fluoresces dark red and the willemite green, franklinite is non-fluorescent. 4" x 3 1/4". From the collection of, and photo by Robert A. Boymistruk.


Bustamite (pink), hardystonite, clinohedrite, andradite garnet (brown), willemite and an apatite crystal (light teal) from Franklin, NJ. 4 1/8" x 2 1/4". From the collection of, and photo by Robert A. Boymistruk.		Bustamite, hardystonite, clinohedrite, andradite garnet, willemite and an apatite crystal from Franklin, NJ under shortwave UV light. The bustamite fluoresces dark red, hardystonite purple, clinohedrite orange and the willemite green, the garnet and apatite are non-fluorescent. 4 1/8" x 2 1/4". From the collection of, and photo by Robert A. Boymistruk.


Bustamite crystals (pink), calcite (white), hendricksite mica (dark brown) with minor andradite garnet (brown), willemite (light yellow) and franklinite (black) from Franklin, NJ. 4" x 3". From the collection of, and photo by Robert A. Boymistruk.		Bustamite crystals, calcite, hendricksite mica with minor andradite garnet, willemite and franklinite from Franklin, NJ under shortwave UV light. The calcite fluoresces orange and the willemite green, the bustamite, franklinite, mica and garnet are non-fluorescent. 4" x 3". From the collection of, and photo by Robert A. Boymistruk.