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PhotosPumpellyite - St. Louis Mine Exploration, Laurium, Houghton Co., Michigan, USA

17th Feb 2014 03:29 UTCKeith A. Peregrine

Pumpellyite Subgroup, Quartz

St. Louis Mine Exploration, Schoolcraft Township, Houghton County, Michigan, USA

Larry,

What a fabulous, fantastic shot! I have enjoyed your contributions from the St. Louis Mine, so much so that I'm adding it to my regular site visits whenever I visit the Keweenaw. Thanks so much!

Keith

17th Feb 2014 21:40 UTCGary Moldovany

Great photo! What exactly are the minerals? looks like you have 4 different species here.

4th Mar 2014 18:44 UTCLarry Maltby Expert

Hi Keith and Gary,

I am sorry for the slow response. I am not familiar with the talk pages and did not notice the notice in my home page until just now.

Keith, the St. Louis is one of the most interesting mines that I have visited in the Keweenaw. The mineralogy and geology seem to be somewhat unique. During the last three years I have spent almost all of my time there. It is one of the earliest flows in the Keweenaw lying just above the Keweenaw fault. There seems to be a large variety of micro specimens there. I do most of my work at home. While I am at the mine I try to select rocks that have vugs showing minerals or small agate amygdules. I usually take about 100 plus pounds home to be broken up and carefully searched under the microscope.

Gary, the only minerals that I see in the vug are quartz and pumpellyite. All of the points in the cavity are reflections off of quartz crystal faces. The large crystal is clear quartz with two clusters of yellow pumpellyite under the crystal and protruding into it making it look yellow. The termination is distorted. The yellow pumpellyite is probably pumpellyite Fe2. Dr. Robinson analyzed three specimens and found that they are clearly pumpellyite and preliminary calculations on the chemistry indicated iron dominance but more work is required to be sure.

Larry,

4th Mar 2014 21:19 UTCKeith A. Peregrine

Larry,

Thanks so much for your comments. Since seeing your photos, I have been greatly intrigued with the mineralogy at the St. Louis Mine. So much so, like you, I intend on spending part of my collecting here and at the Larium dump in the future. Since a kindly gentleman shared his micro interests with me at the Baltic Mine (#2) about four years ago, I have been focusing my eyes more and more on amygdules within the basalt. But seeing your photos has been a delight and inspiration!

Can't wait for the snow melt this year!!!

Keith

5th Mar 2014 01:26 UTCGary Moldovany

Hi Larry. Please forgive my ignorance, I have never seen yellow pumpellyite before, but after looking at some photos in the pumpellyite group pages, I see it occurs in other colors than the common green. I find the green version here in NJ in the traprock quarries and the specimens I find are always micro-sized. If you are ever in my area, drop me a PM and I will gladly take you collecting at one of my favorite quarries. Gary

5th Mar 2014 14:47 UTCLarry Maltby Expert

Thanks, Gary,

I would enjoy collecting with you but my wife and I are getting up in age and we have slowed down on travel. We have had a life time of travel all over the USA and have loved every minute of it! We talk of one more trip to the Black Hills of South Dakota which has been a favorite of ours since the 1960's but even that is unlikely. We can keep in touch on Mindat.

Larry,

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