Melanocerite-(Ce) - Richardson Mine, Cardiff Township, Haliburton Co., Ontario, Canada

Richard Gunter posted a very similar specimen today from the Bicroft mine and a short discussion ensued. Here's what Richard said:
"The problem with these small deposits in Cardiff Township is that there was only one mill besides Faraday in the area. All of the ore from the smaller deposits went to the Bicroft Mill.

I would be more comfortable with the Melanocerite locality being from Bicroft and the Richardson Mine being an assumed locality unless there was an actual find at the Richardson Mine itself. The Richardson Mine was a vein-dyke with a lot of Calcite and not much Quartz, especially Smokey Quartz, and Feldspar. Photos of the Richardson ore (lineated colourless Calcite and fine grained purple Fluorite) have been posted to Mindat. I have a sample from there I have not photographed. The ore does not look like the matrix on this sample.

I did not see any Calcite on the immediate area of the dump when I found the sample. The Bicroft Mine is a pegmatite, much like a simple version of Faraday, that does not contain Calcite but has abundant Quartz and greenish Feldspar. That was the rock in the immediate vicinity of the find so I never questioned its locality. The Melanocerite posted from Richardson looks like it might come from Bicroft.

I hope this helps."

I think it does but I would like to hear what others will say.

I can't say I see any quartz on the sample that couldn't be something else. I have found a similiar looking rock at the Cardiff mine that is a mixture of feldspar, diopside, fluorite, apatite and some unknown REE minerals. There is no reason that similiar material couldn't be found at the Richardson.

Hi Reiner:

It is possible that Melanocerite-(Ce) occurs at both the Bicroft and Richardson localities. The matrix for my posted Melanocerite (Ce) sample (not the one that Rob has posted here) is coarse-grained, massive, slightly smokey Quartz. The sample lacks any mafic phases. Since I collected the sample myself, a long time ago now, I am certain of the locality of the find. As it is a dump sample there was some question as to the actual location in-situ. Have you seen any of the Melanocerite-(Ce) in your investigations of the Bicroft dump?

Richard Gunter

Hello Richard,

Haven't found any melanocerite that I know of yet. It looks so much like thorite and other mixtures I have found that you have to test everything. Unfortunately the only way I can afford to test it is with EDS and that is often inconclusive. I am hoping to get a small piece of confirmed melanocerite to get an EDS pattern I can compare to. At least then I have some hope of finding some. Is the sample you have a confirmed sample?

Hi All,

For what it is worth there was a mill at the Fission (Richardson) Mine that was built about 1931 or 1932. I have seen the mill ruins. Radioactive minerals occur in the calcite fluorite apatite veins but also in the pyroxene syenite pegmatite. Some minor quartz has also been reported although it is not common. Melanocerite was reported by S. C. Robinson as occurring in the pit at the southwest end of the workings.

Hi Riener and John:

No unfortunately this is not a confirmed sample, though it looks like I am going to require confirmation on it. If you have an EDS pattern would you send it to me so I can compare it to my sample.

The bulk of the work on the Bancroft uranium deposits was in the 1950's and that is when the Bicroft mill was used for several of the smaller uranium deposits in the vicinity. The uranium boom did not last long and the Faraday Mine was the only survivor. Did S. C. Robinson give a full description of the Melanocerite? There appears to be several distinct parageneses for the mineral.

Hello Richard,

I have no detailed description of the melanocerite from Bancroft nor a sample. If anyone knows of a reference with some detailed mineralogy please let me know what the reference is.

Reiner