Any Rockhounds Out There?

[Geoman]

Hi all,

A friend on mine just emailed me this tread, as he probably knew I was into rocks. He told me to look at the picture of this cool rock. So here I am.

The rock is a boulder of "BIF" or Banded Iron Formation. There is alternating layers of different material, such as hematite, jasper, etc to produce those neat looking layers. There is another awesome rock similar to that up near the Sudan Mine, in Tower, MN. I'll try and post that picture if I can find it.

Since I am new, thought I would say that I am into rock/mineral collecting, and also coin collecting. I am also an avid fisherman, and hunt also in northern MN. Currently, I am a grad student and my Master's will be in Geology.

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William

[DARK30]

Geoman, Welcome to FM! I'm not exactly a scientist when it comes to these treasurs under foot but I do know a good looking rock when I see it! The one in the photo resembles an agate but then again very different. I do know the rings in a lake superior agate are caused by minerals flowing through the "bubble" and hardening over time...And I would say thousands of years not millions (I'll go with the Genesis account of creation). I have found several rocks with the bandings and rings but are very brittle and lack the color of a real agate. This rock looks brittle also...sure would like to take a closer look!

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cast,cast,cast,cast......

[MT Net]

It was a long trek in. or the first time in 25 years of spring trips, that Friday night, we left the dirty dishes lay were we left them, on the stive and all. Too tired to care about a possible bear. But we survived, althought that late night intruder made us think otherwise...darn mice.

Thanks everybody! I know I learned a few things. Might have to get a polisher now; more toys!

Geoman, lots of interesting fun stuff on this site.

[MT Net]

This just in. I just recieved and email about my rock from the Minnesota Geological Survey. This may be a bit long, so please bear with it, or simply skip this post. Here is the partial response;

"It's an amazing boulder that tells a great story. The boulder can be
classified as "layered or banded, lean iron-formation." I use the word
"lean" because it probably does not contain much iron. Iron-formation is a
sedimentary rock, meaning in this case that it originated as layers of mud
and sand deposited by or in water. The "bacon stripes" are actually layers
of sedimentary rocks: the red layers are iron-bearing quartzose jasper, the
black layers are iron-rich, probably magnetic rock, and the tan layers
appear to be fine grained, iron-poor sediment derived largely from volcanic
activity.
The bedrock geology of the Knife Lake area is a facinating mix of rocks
derived from volcanism and sediment deposition within a narrow,
steep-walled valley that formed about 2690 million years ago. Three main
rock types occur: 1) layers of volcanic lava and sediment, 2) layers of
conglomerate composed of rounded gravel fragments eroded by streams that
flowed off the valley walls, 3) fine grained sandstone, siltstone, and rare
iron-rich sediments deposited in lakes that eventually filled parts of the
valley. Your boulder obviously was derived from the latter group of
sedimentary rocks. Much of the folds in the layers of this boulder formed
while the sediments were still soft, due to compaction by other sediments
laid down atop the iron-formation and by minor crustal movements in this
volcanically active valley. The sedimentary layers were lithified (turned
to rock by heat and pressure), folded, and tilted nearly on-end by
continent-wide crustal compression about 2685-2680 million years ago. This
was followed by a period of many millions of years during which the bedrock
probably eroded slowly, until glaciers scoured the surface between about 2
million and 12, 000 years ago. The most recent of those glaciers-forming a
sheet of ice nearly a mile thick-moved slowly southwestward from Canada and
across northern Minnesota. The iron-formation from which this boulder was
plucked by glacial ice is probably one of several thin and discontinuous
layers exposed to the north and east."

Cool, I'm leading the ice family.

[This message has been edited by MT Net (edited 11-24-2003).]

[Jim W]

Cool rock and cool info MT!!!!

Thanks! I love rocks!

Jim W

[doubleUcubed]

Welcome Geoman! Thanks for more information on the cool rock. Welcome aboard from another "rock" person! This is an awesome site and you just never know what topics can come up!

[Ruttin' Buck]

I'm no rock expert. I've found some fossils, arrow heads, petrified wood, and of course agates.

I'm quite partial to a good piece of quartz. Spent a few summers paying for college by working at a handful of gravel pits. When it was my turn to do equipment checks, part of the job entailed checking the piles to make sure the screens were indeed screening out the right size rock. Well, let me tell you...there must be some huge pieces of quartz out there. There were times when the white rock would just pour off of the conveyor after these rocks were crushed. I have many many pieces of quartz as a result!

My father thought he had the find of the family when he returned from a Colorado trip with an Indian hand axe he found in a river. Well...Mom outdid him. Last summer, while tending to the garden she noticed a burrow in the ground...but no dirt was present outside the hole. She decided to investigate. 6" into the ground was a meteorite! It was awefully scorched and had broke in 2 but it's total size is about that of a tennis ball.

[DARK30]

Teach-D, A good starter tumbler kit in my opinion would be the Thumbler's Model "T". Thats the one I bought for my son and ended up wearing it out myself. See it here...http://www.einsteins-emporium.com/earth/geology/eg933.htm

I picked up a vibrating polisher this fall. Its called a "Lot-o-Tumbler" and is manufactured in Owatonna. I still plan on using the rotary type for some pieces but the Lot-o works in less than half the time.

Remember...Let the kids play too!

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cast,cast,cast,cast......