illustrates the Wightmanite fibres. A close-up illustrates the altering Wightmanite fibres and a different view illustrates the matrix.

The article is posted to assist in the identification of any similar samples that were collected at the Crestmore Quarry prior to the characterization of Wightmanite in 1962.

Location: Crestmore Quarry, Riverside County, California The original description of Wightmanite (Am Min 1962) says it occurs: “half way up the quarry slope from the 910’ level of the Commercial Quarry just below Burnham’s station N”. This may be related to Mineral D of Woodford et al (1941) who says: White, radiating CaMg silicate in peg.- like vein cutting idocrase.

The specimen is: 6 cm x 6 cm x 4cm mass of high temperature calcium silicates: Monticellite, Merwinite, Cuspidine (strong yellow fluorescence in LW), Gehlenite, Spurrite with a 4 cm x 2 cm radiating mass of Wightmanite (tan colour in SW UV) altering to Fluoborite (the mass has a white SW UV fluorescence in the altered part, identical to the literature identification for Fluoborite). The colourless fibres are slightly altered and New Dana says that Wightmanite occurs with Fluoborite and Szaibelyite so the alteration fibres maybe one or both of these phases. Black 1 mm prisms in the Wightmanite mass, growing parallel to the Wightmanite fibres, have the same appearance as crystals identified as Ludwigite in the U. of Arizona sample.

A photo in the Dakota Matrix website, November 13, 2008, of Wightmanite replaced by Fluoborite and Szaibelyite pictured radial aggregates replaced by a chalky white mass with none of the prismatic Wightmanite crystals left. Another photo of less altered Wightmanite, on the same web page still retained the silky prisms. A thumbnail sample of Wightmanite on the Wienrich auction October 6, 2010 shows a radial aggregate of white fibres.

The SW UV response for the unaltered fibres is a medium strength light brown colour; the “tawn” colour that the UV database has for Wightmanite. There is no mention of Wightmanite fluorescence in the Am. Min. article. The original description (1962) says: Wightmanite occurs associated with locally abundant fluoborite and black prisms of possible ludwigite. A note in Am Min (Segnit and Lancucki, 1963) on Fluoborite from the same location says that the samples were: somewhat poikioblastic crystals which were first taken to be scapolite. On further examination, because some of the crystals appeared to be hexagonal, the samples were found to be Wightmanite and Fluoborite. Mindat.org’s Crestmore Commercial Quarry entry says: Occurs as single prisms or radiating clusters of crystals in crystalline limestone in the contact zone on the 910 level. It is supposed to occur with Dolomite, Fluoborite and Ludwigite but the latter is a questionable mineral at Crestmore so this paragenesis needs more work.

The Wightmanite sample in the S. Cal. Raman Spectography page also contains a black prism of Ludwigite, which is also present on this sample. As a borate it was identified as an unknown in 1959 and characterized as a new mineral in 1962, long after the main descriptions of the Crestmore Quarry were written. Murdoch (Am Min, 1961) in his presidential address gave an update on the work at Crestmore. He mentioned this locality in detail but did not give the names to the borates, as they were still undescribed minerals at the time.

Crestmore is a very complex locality for high temperature contact metamorphic silicate minerals. The highest temperature contact zone between a dolomite and an intruding quartz monzonite contained a calcareous sub-zone and a siliceous sub-zone. This is an example of the siliceous sub-zone. The original description of Wightmanite indicates that the analyzed samples were from the immediate area of the 910 foot station that the Spurrite-Gehlenite-Monticellite matrix was found. This may be the coincidence of the boron and Ca-silicate layers contacting. It is the only location where the Wightmanite occurs in large sub-spherical forms.

Compared to equally complex mineral localities at Franklin, New Jersey and Mount Saint Hilaire, Quebec, Crestmore does not have a central location where information about the locality is stored and disseminated. The “Minerals of California” gives a brief summary of the Crestmore Quarry and lists its minerals separately. A copy of the Crestmore description is in the library. Woodford (1941) in the American Mineralogist and Burnham (1959) in the GSA Bulletin examined the Crestmore Quarry in detail. Burnham described the geology and Woodford examined the minerals, known and unknown, that had been uncovered at that time. The sample was probably collected about that time, as it was the last major exploitation of the Commercial Quarry. The detailed description of the minerals gives a much better identity for each of the minerals in this sample.

This sample was purchased at the 1985 Manitoba Mineral Show from Schnieders Rock and Minerals, Poway, Cal. as: Wernierite, Crestmore Quarry, Riverside Co. Calif., with an old handwritten card labeling it “Wernierite, Crestmore Quarry, Riverside Co., Calif.” from J. W. Rodekohr which was provided. Two similar cards are in the MR biographical index. The MR index indicates the collection was dispersed by Mineralogical Research Co. but their card is not included. Jack Rodekohr (1894-1979) is listed in the biographical index with a note from 1940 of: The cabinets of Mr. Rodekohr are outstanding and consist largely of fine crystals and crystal groups. Rare minerals are also a specialty, and his cabinets contain many seldom-seen species." These cabinets were dispersed after his death. Many of his samples went to other dealers and collectors in S. California and his cards have been passed on, as they occasionally appears in the literature and in the commercial mineral websites. Mr Rodekohr would have been in a very good position to acquire rare samples from Crestmore as he was part of the Southern California Mineralogical Society and the note indicated he was a rare mineral specialist.

Fluoborite and Wightmanite closely resemble Scapolite in thin section and these were thought to be Wernerite before re-investigation in 1962. The card number “608” matches a number tag on the sample so the “Wernierite” card has not been misplaced from another sample. The original Scapolite misidentification, mentioned in the Am Min article, was never corrected by Mr. Rodekohr. This is a good example of an error being “frozen” in a collection until it is dispersed to new collector in 1985.

It is probable from the description of the quarry that this sample came from a mass of Monticellite-Spurrite-Gehlenite rock that occurred in the marble on the 910-foot level of the Commercial Quarry. The original sample of Wightmanite was collected from here. The Crestmore samples in Mindat.org and for sale on other internet websites do not have the coarse grained matrix of this sample, they are inevitably on marble. The Mineral D description is of a pegmatitic vein, so this sample is very rare.