Actinolite - Miners Bay, Haliburton Co., Ontario, Canada

1) Can anybody that's collected here provide either a more exact locality description, or a literature reference? I cannot find Miners Bay in Sabina, Traill, Satterly, etc. Somebody help before my head explodes.

(Dave, I'm looking at you. Love your photos, btw.)

2) Very uniform looking material from here in the d-base, most being called tremolite, but two going under actinolite. I'd strongly suggest moving the two under actinolite over to tremolite. Not worthy of a big discussion on sight-ID'ing amphi/xenes, though I'd love to hear if anybody has an analysis.

3) One of the tremolites photographed is very suspicious looking; with the tabular habit, x-section, etc. of a fluororichterite from the Earle Property. Very different from Miners Bay tremolite. Perhaps somebody can look into it further.

Hi Tim,

I've been there and can drive there but don't think that I can actually give you directions! The ocality is on the east side of the main highway near Miner's Bay. I could put you in touch with someone who probably knows the actual cross-road, if you'd like. Let me know?

Cheers,
David KJ

If it's not too much trouble, Dave, I'd really love to pin this one down. It's interesting material and I'd like to check it out some day. Drop me an email or whatever - tjokela@execulink.com

Thanks for any further info.

Tim, in the old days if it was white, its tremolite, dark green its actinolite; I was just going with the flow. Pending yet another reclassification of amphiboles, there really is no justification for actinolite as a distinct species.

Has anyone analyzed this material? Would like some guidance prior to changing the species

Jeff

Hi Tim:

I was at the locality in May 1978. It is on the north side of Clear Lake Road approximately 100 meters east of the highway through Miners Bay. It is not a large locality, 6 meters long by 2 meters in height, so there may not be much left of it. Olav has contacted me and I have sent him the information I have regarding the amphibole chemistry.

The occurrence is in a dark gabbro and does not resemble the classic vein-dykes of the Bancroft area. I have several other samples than the one I posted so if you are interested I can provide other photos of the paragenesis.

Richard Gunter

On my inquiry, Richard sent me the following information ( I hope you don't mind me quoting part of a private message in an open forum):

"The chemical analyses I mentioned are from an enquiry I did with David Joyce. He answered my e-mail on December 17, 2009 and said: This back from M. Picard, from my inquiry at the CMN. “Our database shows for these amphiboles that there are more often tremolites than actinolites. 3 analyzed specimens gave a tremolite result and only one gave a border line tremolite-actinolite result; so you either name them tremolite-actinolite to be on the safe side or simply tremolite as being the most probable analysis result”.

There have been other amphibole analyses from the immediate area published. Analyses of clinoamphibole from the Miner’s Bay area in the 1997 CJES article has two samples of Tremolite and one sample with approximately equal Fe and Mg. These may be the analyses Picard was referring to; they have Mg:Fe ratios of 2.58, 0.93 and 1.69. All are completely Ca dominant."

I guess the tremolite/actinolite ratio of the uploaded photos are about right, except that we don't know which ones are tremolites and which ones are actinolites. May I suggest that following:

- We label all photos uploaded to the database as tremolite-actinolite series, how the specimens are labeled in your collection is sort of irrelevant in this context

- I update the mineral entries for the locality with the information provided by Richard, stating that most of the amphiboles from this locality will be tremolites, but that some of them will be actinolites.

I think that would be the most "correct" way to deal with this, as if there ever will be a "correct" statement on amphiboles.

Any thoughts on the matter?

Olav

Hi Olav:

That sounds correct, though an additional note might be included that these crystals are not colour zoned so there is no method of visually determining which part is higher in iron or magnesium.

Richard Gunter

Thanks to all for the clarifications!