JOHNBAUMITE



Johnbaumite is a calcium arsenate hydroxide mineral of the apatite group and the hydroxyl analogue of turneaureite. The analysis given by Palache calculates as a poor one but, if reasonable, is of what is now known as johnbaumite; the same is true for that given by Bauer and Berman (1930).
Johnbaumite was described from Franklin by Dunn et al., 1980a) and from Sterling Hill by Jenkins (1994).
Johnbaumite is known primarily as massive material, gray-white, with a greasy to subadamantine luster. Small crystals were reported by Jenkins (1994). The hardness is approximately 4 1/2, and cleavage is distinct. The density is 3.68 g/cm3 (meas.) 3.73 g/cm3 (calc.).
Johnbaumite fluoresces with an orange color in shortwave ultraviolet, but this is not diagnostic. It is easily confused with other arsenic apatites and is best verified by a quantitative water determination, coupled with X-ray methods.
Johnbaumite was found in a small lenticular body located at 830S, 170E, in the 730S Palmer Shaft pillar, in the third sub-level below the 750 level in the Franklin Mine in 1944. Johnbaumite is host for an occurrence of Franklin yeatmanite (Dunn and Leavens, 1980) and is also associated with diopside, andradite, copper, franklinite, and romeite.
Prismatic, gray crystals, over 4 cm in length and approximately 1 cm wide, were found on the 1200 level at Sterling Hill, associated with white calcite, barite, sonolite, zincite, and adelite, and are best referred to as johnbaumite-svabite. They are both F and (OH)-bearing, but their F/(OH) ratio is uncertain; preliminary studies suggest they have (OH) > F. However, they are rimmed with and contain inclusions of minute crystals of adelite; bulk water determinations are therefore suspect. Another probable Sterling Hill occurrence was described by Jenkins (1994).
In general, Sterling Hill apatites are Ca-AsO4 members of the group and, because fluorine is less abundant here than at Franklin and (OH)-bearing minerals are common, johnbaumite may be locally abundant. (Dunn, 1995)

 Location Found: Franklin (Type Locality) and Ogdensburg
     
 
 Year Discovered: 1980
     
 Formula: Ca5(AsO4)3OH
 Essential Elements: Arsenic, Calcium, Hydrogen, Oxygen
 All Elements in Formula: Arsenic, Calcium, Hydrogen, Oxygen
     
 IMA Status: Approved 1980
     
Fluorescent Mineral Properties
 Shortwave UV light: Bright to weak orange
 Mid wave UV light: Orange
 Longwave UV light: Orange
 Additional Information: Brightest at shortwave
     
 To find out more about this mineral at minDat's website, follow this link   Johnbaumite

     
 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.651
The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 58, No. 1 - Spring 2017, pg. 11Fluorescent Minerals of Franklin and Sterling Hill, N.J., Part 2, Richard C. Bostwick - Johnbaumite
View IssueV. 45, No. 1 - Spring 2004, pg. 12The 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 - Johnbaumite
View IssueV. 35, No. 1 - Spring 1994, pg. 21Geology and Mineralogy of a Veinlet Assemblage Associated With Wollastonite-Bearing Rocks, Sterling Mine, Ogdensburg, New Jersey, Robert E. Jenkins II - Johnbaumite
View IssueV. 33, No. 2 - Fall 1992, pg. 11The Check List of Franklin-Sterling Hill Fluorescent Minerals - Johnbaumite (Fluorescent Info)
View IssueV. 22, No. 1 - March 1981, pg. 4Mineral Notes Research Reports, Johnbaumite
View IssueV. 21, No. 2 - September 1980, pg. 5A Mineral New To Science, Johnbaumite
     
Images
     
Johnbaumite vein in franklinite and willemite ore from Franklin, NJJohnbaumite vein in franklinite and willemite ore from Franklin, NJ under shortwave UV Light
Johnbaumite vein in franklinite and willemite ore from Franklin, NJ. 3" x 3". From the collection of Zack and Ralph Bonard, photo by WP.
Johnbaumite vein in franklinite and willemite ore from Franklin, NJ under shortwave UV light. The johnbaumite fluoresces orange, willemite green, and the franklinite is non-fluorescent. 3" x 3". From the collection of Zack and Ralph Bonard, photo by WP.






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