Rocks In My Head

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In Europe and elsewhere there's a Carboniferous epoch.  We in the U.S. divide the Carboniferous into the Mississippian and the Pennsylvanian.  Like those of the previous periods, the Pennsylvanian rocks have been eroded away in Minnesota.  However, elsewhere the landscape was dominated by swamp, tree ferns, and horsetails.  Compaction turned the vegetation into bituminous cole.  During this time the Canadian shield was uplifting.  The entire continent was tilting westward.




Posted by oh5/ojhoff at 2:41 PM CST
Updated: 01/05/12 3:18 PM CST
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minor disappointment
My grandfather liked to grind opals.  He also enjoyed experiments, gadgets, discoveries.  How jubilant he would have been to learn that his daughter, my mother, had created cabochons that resembled opal, out of casting resin and Christmas glitter flakes.  But he was gone by the time of her discovery, and now she has also passed away.  I don’t think her cabochons resemble opals that much, but Grandpa and my mom would have pretended.  That’s the way they were.  I have an entire drawer of her creations.  Opal-like or not, these ovals and shapes are attractive and lovely.  I wear them in the jewelry she made, and I give them as gifts.For some people, lapidary meant grinding shapes, mostly ovals, and setting them in mass produced rhodium plated mountings.  Then there was a movement to learn jewelry making with precious metals.  That meant shaped, handmade mountings and freeform stones.  I would like to learn wire wrap but until I do, I am clearing out the mountings and findings that I inherited from my family.  My collection goes back a half century, back to my earliest memories.  I have a webpage where I sell these metal pieces and other craft supplies at rock bottom prices.  Sometimes when I box up these pieces of my past and ship them off, I feel sad.  But space is precious, confusion is counterproductive, and sometimes I have a cash flow problem.At one of these times I decided to sell my already severely discounted findings at half price.  I got a few orders, including one that I had second thoughts about filling.  One woman sent me 12 emails regarding a very small order.  She wanted to make sure she got her money’s worth.   I should have seen the writing on the wall.  This interaction was doomed from the start.  I boxed up her stuff, being very generous about enclosing extras.  Extras from my cache of precious memories.Was she satisfied?  No.  She said she could not “selvedge” any of the stones from at least 60 sets of my mother’s jewelry.  Had she removed them from the cards and gave them a swish through jewelry cleaning liquid from the dollar store, she would have had at least a $300 collection of costume jewelry.  There was something wrong with the blanks for making cross necklaces.  But then, she paid about $1 for the entire bag of 50 pieces.  The items she admitted liking were my free gifts to her...including hand painted tree rounds.  Dozens of them.  She said opening the box was a grave disappointment.  And the items smelled like mildew, she said.  The odor was overwhelmingFor that I am truly sorry.As somebody who grew up in the lapidary culture, the odor of mildew is something I take for granted.   Rock shops were housed in outbuildings, sometimes with leaky roofs, and specimens stored in broken down cardboard boxes.   The email from that customer was a disappointment to me, too.

Posted by oh5/ojhoff at 9:30 PM CDT
Updated: 10/29/11 9:34 PM CDT
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I bought another geology book by the same author as my last purchase.  A customer stopped by and gave it a high recommendation.  Reviewers complained that much is repeated from the author's other book.  I did not find this to be the case.  Of course, I am the one who still reads from the book my uncle used at the U of M in the 1950's.

Some day soon I want to go on a rock hunting trip.  This can take one of three forms. Either I will go somewhere that has geological features I can photograph.  Or somewhere I can pick up samples in the field.  Or, somewhere that I can visit a rock shop.



Posted by oh5/ojhoff at 12:54 AM CDT
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Adventure Publications

Adventure Publications continues to send me nice gifts.  I will handle their products when it's feasible (when I get my road signs back).  In the meantime, I can recommend them heartily. 

Here is their information.



Adventure Publications, Inc.
820 Cleveland Street South
Cambridge, MN55008 

(8-5 Mon-Thu, 8-4 Fri CST)

1-800-678-7006 (toll-free)

Fax: 1-877-374-9016 (toll-free)


 In addition to nature books they sell mysteries, cookbooks, Scandinavian humor, children's books, memoirs, poetry, history......


Posted by oh5/ojhoff at 1:49 PM CDT
Updated: 08/23/11 7:04 PM CDT
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Another nice surprise from Adventure Publications!

Posted by oh5/ojhoff at 6:53 PM CDT
Updated: 08/23/11 7:07 PM CDT
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The Storied Agate

Yes, I'm still reading Minnesota geology, but but I received a complimentary copy, from Adventure Publications, of a stunning paperback titled The Storied Agate: 100 Unique Lake Superior Agates

Posted by oh5/ojhoff at 10:39 AM CDT
Updated: 06/23/11 5:18 PM CDT
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The Mississippian period in Minnesota is like the two earlier geologic periods.  Information is obtained from other areas as there is very little evidence left in the state.  Warm shallow seas were probably homes to crinoids (sea lilies).  Also, amphibians were likely to have lived near rivers, lakes and other wet areas.  Land plants had developed, but not flowering plants.

I have discovered a new aspect of stone collecting that appeals to me very much.  Suiseki is the Japanese word for viewing stones.  That is, stones presented in their natural state and appreciated as works of art.  The practice began in China, where the objects are known as scholars' stones, or Gongshi.  The Koreans also have their variation of this art.  There is is called seosuk.  Western cultures have begun to adopt yet another interpretation of this type of artistic presentation.  In Japan, it is often associated with bonsai. In Western culture this art is in its infancy and is still evolving.  I hope to contribute to its evolution, now that I have discovered it.

Posted by oh5/ojhoff at 9:31 PM CST
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rock shop history

In lieu of a blog entry I am attaching two files of the article I wrote for Good Old Days about my family's rock beginnings.

Posted by oh5/ojhoff at 6:34 PM CST
Updated: 06/23/11 5:20 PM CDT
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new rock shop in town

I thought I saw a new store front business in town, and it was a rock shop.  Then I thought to myself, I must be mistaken.  Nobody in their right mind starts a rock shop.  Wow.  Did I really say that out loud?    I have been fighting this attitude for years, and I've blogged about it and raved about it, and now I've fallen prey to it myself.  Yesterday I found an ad in the classified section of the local shopper.  I was right.  Someone has started a rock shop downtown.

My parents had a rock shop.  So did my grandfather.  My parents were told in both subtle and not so subtle ways that rocks are a hobby, not a business.  As I see it my parents were beaten down by this attitude, persistent and relentless,


until they believed it themselves.  I often wonder why the nosy neighbors and others (I don't really remember who it was) couldn't have afforded them the dignity of  calllng it a seasonal business.  Which it was.  Kind of like a resort.  They would have felt much better about themselves.  Confidence and support might have pushed their enterprize into a more viable arena.  My parents were too poor for hobbies and they used every dime for living expenses.  Sometimes I could cry.

People try to pull that s*** on me too.  When somebody stops in and refers to my hobby I try to set them straight but my first impulse is to say &%#@$%^.  And no, this isn't a hobby farm. This is where my grandparents made a living and raised seven kids.

A new rock shop in town!  Competition?  No, not at all.  Just wind in my sails.

Posted by oh5/ojhoff at 11:09 AM CST
Updated: 06/23/11 5:24 PM CDT
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shell pearls
I bought some shell pearls just to see what they are like.  They are lovely!  The shell pearl is manufactured out of shells, and start with the same process used to create the shell nuclei that is the beginning of a cultured pearl.  The shell is then shaped manually...and painstakingly.  Then it is drilled, strung, dyed and baked.  Many colors are available.  Finally, the pearl is polished and strung for the second time.  There are many quality controls built into the process, and in the end, a shell pearl can pass for a cultured pearl.  Just so you know.  Jewelry designers love shell pearls because they come in large sizes and their appearance is so delightful.  As one website states, "They should be enjoyed".

Posted by oh5/ojhoff at 9:11 AM CST
Updated: 08/23/11 7:08 PM CDT
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bummed out

I am really bummed out on a trade transaction I made via the forum Dirty Rockhounds.  One person was pleased with what I sent and recommended me for another trade.  Another person didn't say anything.  The third person was "dissapointed", and very sarcastic with me.  Her reaction left me dumbfounded.

The last cabochon my 96 year old grandfather made was  brown stromatolite which is not flashy but is very interesting.  It is an 8 billion year old MN fossil, the earliest life form.  Red stromatolites are considered gem quality.  I sent her both.  My parents and grandparents signed a waiver and went into the now underwater Mary  Ellen mine to gather this material.  Larvikite, from Norway, also known as Swedish blue pearl, is the stone we used to make both my grandfather’s and mother’s gravestones.  A friend who works in mines has been to all 3 larvikite quarries in Norway.  90 percent goes to waste because it has to be cut at just the right angle to take advantage of the “sparkles”.  My uncle made it into beautiful belt buckles.  I could go on and on.  Every stone has a story.  Since she was so unhappy I offered twice to send out another box if she would send me her mailing address again.  But I got no response.  It makes me wonder if my family has been dealing in such worthless crap for over sixty years maybe we shouldn’t have been in business in the first place.

Posted by oh5/ojhoff at 10:04 AM CST
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The same as with the Silurian, there is not a lot of evidence of activity from the Devonian period in Minnesota.  An exception is a carbonate unit called the Cedar Valley formation in southern Minnsota.  The material was deposited by the advance, then the withdrawal, of marine waters.  Most of the fossil evidence has been obliterated. Elsewhere in the world there is fossil evidence of bizarre fish types, swamps and forests, and primitive amphibians.  It is a fascinating era, for anyone who enjoys reading about the earth's history.


I have received two boxes of rocks and minerals in trade, from contacts I made at Dirty Rockhounds, a site for earth science enthusiasts.  Beautiful quartz from SC (Diamond Hill Mine), and others from a collector in WV.  Now I have to do a good job of selecting items for my end of the trade :)

Posted by oh5/ojhoff at 1:56 PM CDT
Updated: 10/26/10 2:01 PM CDT
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According to the geology books, there are no Silurian rocks in Minnesota.  Elsewhere there is evidence of primitive plant life, mosses and corals.  There may have been vascular plants.  But Minnesota was a barren peneplain covered by a very hot sea.  The equator passed right through the middle of the state.

I am about to fill in gaps in my rock inventory with a few ordered items:  turquoise in forms ranging from good quality cabochons to chalk to beads;  carefully chosen fossils including coprolite, and my continuing  acquisition of affordable examples of the traditional and alternative birthstones.  I opened the tumblers and found that most of the materials have to go back in.  Haven't gotten together with the "ladies" to do wirewrap yet.  I gathered up all the white rocks for prep and painting during the coming winter...which unfortunately is on its way.

Posted by oh5/ojhoff at 3:03 PM CDT
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Hubbard County Geology
It frustrates me that I cannot seem to find much about the geology of my own county, but I keep looking.  Lately I've discovered that most of the rocks are from the early proterozoic, which was when the gathering up of oxygen in the earth's atmosphere took place.  It was a time of major glaciation.  Life consisted of complex single cell organisms, and some multi-celled.  Other rocks are from the late archaen, which preceded the proterozoic.  The atmosphere lacked free oxygen.  Liquid water was present.  Temperatures were close to modern day temps.  Stromatolites were present.

Posted by oh5/ojhoff at 2:52 PM CDT
Updated: 08/23/11 7:20 PM CDT
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rock record

The rock record of depositions from weathering is well exposed in southern Minnesota.  There are many sandstone formations, along with some shales, named after area towns.  The Mt. Simon sandstone has rounded sands which indicate high energy deposition, strong waves and currents.  The material contains quite a few brachiopods.

The Hinckley Formation is similar to the Mt. Simon but the latter contains more feldspar.  The Eau Claire Formation is fine grained, suggesting that it was formed under quiet, calm conditions.  

Galesville Sandstone is coarse grained, likely formed under high energy conditions near the shore or beach.  The Ironton Formation contains silt as well as quartz and rests on the Galesville Sandstone, suggesting perhaps that the sea withdrew and redeposition under calmer conditions ensued.

The Franconia Formation is characterized by abundant glauconite, which forms on the sea floor under oxygen poor conditions.  The Saint Lawrence Formation is characterized by carbonates but also contains silt, clay, and sand which indicate fluctuating conditions.  Jordan Sandstone is coarse-grained and contains pebbles, indicating it was formed near a shore or beach.  These formations are interesting as a record of the seas that once covered Minnesota.

Sweltering here a couple of days ago, but now it's cool and almost like fall.

Posted by oh5/ojhoff at 11:24 AM CDT
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Post pre-cambrian
The post pre-cambrian time in earth's history is the span of years that ranged from 600 to 2 million years ago.  The most notable aspect of this period is that shallow seas covered much of the north American continent, seas that would encroach and then recede.  These seas were different from earlier ones in that they were home to plants and animals.  Each time the seas would spread across the land it would bring with it a new mixture of plant and animal types.  Some of the animals developed hard shells and skeletons which today are found in the various sediment layers left behind when the seas subsided.  It is thought that these skeletons and shells were developed to protect creatures from ultraviolet radiation, from the stress of waves and currents, and from predator stress that occurred in more crowded ecological niches such as near the shores.  Minnesota wasn't as cold during most of this time period.  These marine environments were tropical to subtropical and contained corals as evidenced by the fossils. 

Posted by oh5/ojhoff at 6:27 PM CDT
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late precambrian
The late precambrian is like a puzzle.  There are difficulties in determining ages of things and sequences of events due to the fact that without fossils, its impossible in most cases to do radiocarbon dating.  There are, however, three distinct ages of rocks.  The oldest are quartz sands, which suggest a widespread sea.  Then the volcanic rocks, the time period during which escaping gasses formed bubbles in which the now highly desirable Minnesota agates and thomsonites were formed.  After that came a period of erosion and sedimentary deposition of sandstones.  The area known as the Duluth Complex (because it is so complex) has many colorful minerals that sound like they would be of interest to the collector.  I don't know if there are any collecting areas there, though.

Posted by oh5/ojhoff at 5:11 AM CDT
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rock shop cleaning

No time or energy to read up on geology.  We are expecting 300 barn guests and I want to have my shop looking decent in case some decide to visit it.  I really could use a lot more inventory.  When I rearrange things, blank spots appear.  Today somebody visited my shop, a fine person I am sure, but he had a forceful way of asking questions, and I was at a disadvantage because I wasn't expecting it.  Anyway, he asked how long I had lived on the property and I said all my life.  He responded by speculating on how long a life I had lived, and he guessed accurately, which made me damn $%^&**ing mad.  I'm used to people either underestimating my age or holding their tongue.  Maybe time has caught up with me, or I have to get back on the treadmill, comb my hair when I get up, and wear make up not just for special occasions anymore.  !@#$$%^^&&

I made a good trade the other day, jasper and hematite for copper and turquoise and similar ores including lead silver.  

Posted by oh5/ojhoff at 10:20 PM CDT
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What's new?

I haven't done any research I can blog about, unless I count a couple of articles sold to Mechanical Turk that were based on earlier research.  I wrote about carnelian and crystalline quartz.  I have a facebook page for my business now, and quite a few fans.  I sorted through the newly opened small tumblers again, but a lot of that stuff has to go back in the polish.  As usual, some were gorgeous and some are pretty rough.

 If anybody at all is reading this blog, check out Hoffs Rock Shop on Facebook.  I post different pictures than the ones on my site.

Posted by oh5/ojhoff at 11:18 AM CDT
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The Middle Cambrian

The Middle Cambrian is what we call the time period from 2500 to 1600 million years ago.  It is important to the economic history of Minnesota, and to the development of this nation as an industrial giant.  Why?  Well, sometime during this era, the atmosphere changed from one rich in carbon dioxide to an atmosphere rich in oxygen.  This happened because of the development of colonies of green marine plants.  The oxygen released iron in the underlying rocks and deposited it as hematite (iron ore), which makes up the iron ranges in Minnesota.  This happened world wide.  The iron ranges on other continents have been determined, by geochronologists, to be the same age.  Other interesting geological events happened in Minnesota around this time, including some mountain building, but this one was probably the most spectacular. 

 I opened up the small tumblers and found some nice Minnesota agates and other agate, jasper and quartz material.  Also, I ordered tumbled rocks, to get more variety and to start making sure I have reasonably priced examples of all the birthstones.  I started with January, and ordered garnet and rose quartz.  Then put the rocks that needed more polish back in the tripoli powder.  I still don't have road signs but I'm carrying on as if I did :)

Posted by oh5/ojhoff at 9:20 AM CDT
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