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Rock Shop
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haven't blogged for a while

This weekend I set up a rock display at a jumble mart.  People asked me, Do you polish all these rocks or do you just buy them?  The truth is, I do both.  My current emphasis is on purchased inventory.  What I did was set out to make available  every months traditional birthstone and its alternative in a form that is affordable.  In many instances this means tumbled baroque stones.  Some were hard to locate.  Others are in rough crystal form and will need to be face polished.  Yes, I own a rock polisher.  In the meantime I am selling them as is. The traditional January birthstone is garnet.  In its most popular form, a sort of dark red but can be any color.  The alternative is rose quartz.  Februarys stone is amethyst and the alternative is black onyx, which is the earliest example of a dyed or altered stone.  Pliny the Elder, historian of ancient Rome, writes about the method in his work on natural history.  March is aquamarine, a form of beryl.  I had a hard time with this one and resorted to ordering a pound of tumbled stones from Amazon, which I was not satisfied with, so I am searching some more.  The alternative is bloodstone, a form of jasper.  April is diamond.  I ordered boart (a small granular diamond used for abrasive) and put it in a small vial with a cork stopper.  The other April birthstone is rock crystal.  May is emerald, a form of beryl, and the alternative is chrysoprase. I located pieces of rough chrysoprase from Madagascar.  June has three stones.  The most expensive is alexandrite, a form of color-changing chrysoberyl.  I ordered a package of four pieces from India and had to sign for them when they arrived. Small ziplock bags were nowhere to be found in town so I didnt bring them to the Jumble Mart.  The others are moonstone and pearl.  I filled vials with small pearls in natural colors, mostly white, pink, gray and light gold.  July is ruby, again tumbled but rather expensive, and carnelian.  August is peridot.  I filled vials again.  My source for these was the San Carlos Apache reservation.  If this stone is found in the U.S. its pronounced as spelled, but the Europeans call it peri-doh.  The alternative is sardonyx.  Mine is tumbled but this material can be used to carve cameos.  For September I found some rough blue sapphire crystals.  If they dont polish up nicely I am going to look further.  Im not satisfied with the alternative lapis lazuli (a rock, not a mineral).  It looks too much like cubes.  October is a interesting and complicated.  I have common opal from Madagascar, which is drab green, but when most people think of opal, they envision fire opal.  So I do stock a few opal triplets with visible fire.   Also, I purchased something called opal quartz girosol, which I had never before seen.  It’s quite a bit like rock crystal quartz.  The other is pink tourmaline.  I have a few samples.  Fortunately there’s not a lot of demand for it.  November is yellow topaz.  I had the most beautiful tumbled examples but those are not currently available.  I found rough topaz.  Again, face polishing might improve their appearance.  The alternative, citrine, is available in tumbled form, and as small crystal clusters.  The grade A was not available in large tumbled pieces so I might try that one again and accept an order of medium sized.  December is another month with three alternatives.  Turquoise, widely available, mostly because of its popularity.  Blue zircon which I failed to locate except for a few small faceted pieces, and tanzanite.  I took apart a string of minuscule tanzanite beads and put it in vials.  Even as rough crystals, it’s way over priced.  Gathering together all these birthstones has been tiring, but in another sense, it has been an adventure.   And, its ongoing.  






Posted by oh5/ojhoff at 8:23 PM CDT
Updated: 09/29/19 8:34 PM CDT
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outdoor learning center
A few years ago I was visiting my uncle (now deceased) and my aunt and they had dropin visitors curious about their wind generation.  I researched the group that was showing interest in their windmills and found out they represented a very worthwhile outdoor learning center.  This would be a good place to take a field trip.
The simultaneous utilization of more than one renewable energy source can result in a spectacular reduction in costs and can diminish a carbon footprint.  The Deep Portage Learning Center of  Minnesota is proof.  In places such as these, children, adults, and families gather to  learn  valuable skills like conservation, resource management, and environmental protection, not to mention all around enjoyment of the outdoors.  Central to these activities is renewable energy generation.

Northern Minnesota, known for its long, cold, snowy winters, would not seem like a   prime location for solar  energy generation. However, the solar potential is as great as some southern regions.   Deep Portage, a center that focuses on environmental awareness and education, has built a number of solar energy systems that heat classrooms, supply hot water, and provide electricity.  The electric system is tied into the grid and offsets the center's monthly energy costs.  Two solar powered furnaces provide forty percent of the heat for two of the classrooms, even during the coldest months of the winter.  The furnaces were installed by the Rural Renewable Energy Alliance located in nearby Pine River, Minnesota.  Their  solar hot water system provides seven hundred gallons at peak production, which is eighty percent of their need at times when the center's enrollment is at full capacity.  The solar classroom system is two-sided and is powered from the top as well as reflecting light from white rocks at the bottom.

Northern Minnesota  has ample wood resources, so switching from propane heat to wood gasification at Deep Portage was probably a logical step.  The main building  burns eighty five cords of wood in a typical winter.  They use a pressurized wood boiler rated at five hundred thousand BTUs per hour, and a similarly rated non-pressurized  furnace.   The Interpretive Center building uses a  turbo pressurized wood boiler manufactured in Austria that is rated at one hundred seventy BTUs per hour.  Energy efficient fireplace inserts heat the great hall and the dining hall.  The savings in one building alone, after conversion from propane, averages thirty five thousand dollars per year.

Two wind turbines produce ten kilowatts at peak power.  The output amounts to over seven thousand kilowatts in a month's time.  With its seventeen foot blade sweep, the larger of these windmills towers over the campus as an iconic symbol of green energy.  

In addition to renewable energy generation, Deep Portage is a model for conservation and green living.  For example, the placement of windows allows for maximum utilization of natural light and sunlight.  Many of the buildings were constructed using local granite.  Classes teach self reliance and an appreciation for the environment and the natural world.  The activity list seems endless:  canoeing, fishing, bird watching, archery, snow shoeing, science, forest management, plant identification, basics of hunting and gathering, crafting from recycled materials, foraging, orienteering, journaling, nature drawing and aquatics,  and a hundred other paths to an enlightened lifestyle.

Deep Portage Learning Center is one of many such campuses across the nation and around the world where education, recreation and community building take place in these amazing indoor spaces and outdoor classrooms.

Posted by oh5/ojhoff at 2:09 PM CDT
Updated: 03/22/16 2:15 PM CDT
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long time no see
Not going to continue blogging about Minnesota geology and glaciation, for a while anyway.  Life has taken a few turns.  I will keep my current website but am going to set up another, not a mirror site, just an additional one, that is more device friendly.  Life takes its twists and turns.  Going into gardening and production of dairy products.  Trying to set up a community center/theater.  But I retain my interest in earth sciences, lapidary, rocks, jewelry, arts and crafts, etc.  

Posted by oh5/ojhoff at 6:05 PM CDT
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long time no blog
I see that it has been months since I wrote anything here.  I wondered why I had no energy.  Then one day I was in terrible pain, and ended up having a lithotripsy.  They broke up a 10 mm. kidney stone with sonar waves.  I told the surgeon I was an amateur mineralogist and he assured me that stones forming in the urinary tract aren't silica based.  However, I was informed by a visitor to my website that I had made an error identifying a mineral specimen I had gotten in trade.  I called it a thunderegg because that's what I always called solid "geodes".  Apparently thundereggs are formed in volcanic areas, technically speaking.  It was a yellowish mineral that if I had soaked it in oxalic acid might have turned to calcium oxalate.  Which was the chemical composition of my kidney stone.  Everything comes around in a circle.

Posted by oh5/ojhoff at 5:21 PM CDT
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More Ice age stuff


 There is a history behind the appearance of the Minnesota landscape.  A warming trend began about 13,000 years ago.  This set off many events related to glaciers and water.  Water returned to the oceans, the levels of which rose.  Flood from meltwater (from the retreating Laurentide Ice Sheet) created a system of streams and rivers.  As the glaciers retreated, they left behind piles of sediment called recessional moraines.  Around this time, underground caverns formed where the ice flow was stalled.  When finally this dead ice melted and the caverns collapsed, a landscape of hills and kettle lakes emerged.  In Minnesota, this process was comparatively swift.


I really would appreciate if anyone reading this would take a look at my ebay listings.  My ebay name is ojhoff218 




Posted by oh5/ojhoff at 9:02 AM CST
Updated: 03/03/15 9:27 AM CST
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wisconsin glaciation
The landforms that make up Minnesota today were left behind during the time period that is now known as the Wisconsin Glaciation.  Tongues of ice formed and retreated many times.  Early history of these episodes are speculative because evidence has been obscured by later glacial activity.  Wood from beneath the oldest deposit goes beyond the capability of radio carbon dating and so must be 40,000 years or more.  The next advance of ice was perhaps 34,000 years ago and it left behind significant amounts of limestone fragments.  Till deposited in this advance is visible on the Iron Range (in the open pit mines), in the Twin Cities, and along the Minnesota River.  Landforms in west-central Minnesota show that the Wadena Lobe shrank, then readvanced to form the Alexandria Moraine, which is impressive in height and breadth.  Eventually the flow of ice stopped and collapsed into a moraine dotted with lakes.  Almost 20,000 years ago, the glacier making processes slowed.  The huge glacier known as the Rainy-Superior melted and developed tunnels of meltwater.  The hydrostatic power of the melt water was so great it created cut deep valleys into the floor.  Eventually the tunnels collapsed and deposited ribbons of sand and gravel within those valleys.  Glaciation had not entirely ceased.  14,000 years ago there was a reservoir of ice in the north of what is now the Canadian border.  There were several short advances before full retreat.  After that, the now familiar landscape of present-day Minnesota emerged from the former ice sheet.

Posted by oh5/ojhoff at 10:14 AM CST
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after Christmas

Still can't wrap my head around Wisconsin glaciation.  Maybe later today.  It has been 2 months since I blogged here.  The year has been difficult in the extreme.  Lost five family members, also a dog and a cat.  I have been selling on ebay, although not much.  Neighborhood projects have taken over my time and energy.  Maybe that's a good thing.  I don't think anybody reads this blog.  I might get more blog readers if I am more consistent about posting.

I post my ebay auctions in the various rock and mineral groups on Facebook.  Each group has its own rules.  It's hard to keep track so I read them over each time I post.  Well, I made a mistake and posted an auction where I shouldn't have.  The group administrator was very nasty to me and of course I answered back (but not before I tried to apologize).

 I managed to catch her name before she blocked and banned me.  Interesting.  She's from an area where I have scores of relatives.  Some are well-placed in the fields of earth science, literature, computing, etc.  I'm not a name dropper but jaws might indeed drop.  Others live near prime collecting areas for rocks and minerals. One cousin said he frequents the area where ellensburg blues are found.  He's not a rockhound but he said he'd keep an eye open.  Another relative I met on Facebook has three colors of jade on her property.  The person who blocked me is a writer.  Another family connection is the co-founder of a writer's center.  I've not even scratched the surface.  One of my downfalls is that I keep thinking about things like this.  

Posted by oh5/ojhoff at 8:25 AM CST
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fall day, pleasant customer, resuming my reading of Minnesota geology

The day was windy, but sunny.  I had a customer to my shop.  He was considerate and called ahead.  A pleasant visit.  In the fall and winter, rock shop customers tend to be of the online variety.  I picked up my book Minnesota's Geology by W. Ojakangas and Charles L. Matsch once again.  I left off reading about Wisconsin glaciation, which was the last of the glacial periods and began around 75,000 years ago.  Skimming the material, I felt I didn't understand its intricacies well enough (yet) to blog about it.  

 Last week I was called dumb as a rock in one of my Facebook groups.  Or maybe it was more than a week ago.  It was a disagreement over nomenclature.  When someone is that blunt, I question myself.  Am I really dumb as rock?  I revisited my birthstone videos.  Yes, I could have googled that material and put them together.  But that's not what happened.  I carry around in my head a lot of facts and ideas.  I didn't regurgitate them from a questionable website. Even someone who uses Wikipedia as a primary source has to have some knowledge or interest, to even know where to begin.  The quality of those videos is better than I remember them. 

Posted by oh5/ojhoff at 6:00 PM CDT
Updated: 10/21/14 6:27 PM CDT
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rock customers from Hell

There is a cultural difference between northeastern and northwestern Minnesota.  Since it’s not consistent, some may deny it exists.  I am referring to regions known informally as the valley and the range.  My maternal grandmother was from the Red River valley and I understand that mentality better.


I have observed that people in charge of something…parking, what door to enter, etc….out by the river will tell you when you are breaking the rules,  with discomfort and reluctance, and sometimes they will just let it go.  People on the range are quite comfortable with enforcing rules.  They can be quite vociferous about it, even when it’s not a matter under their direct jurisdiction.


I remember going to a family reunion with my parents (both gone now) and we stopped into a cafe in Ada, Minnesota.  My dad was worried because it was Sunday and no gas stations were open.  We were almost out of gas.  Somebody said there was a station open in Twin Valley if we could get there before it closed.  A man in the cafe said, with a slight Norwegian accent, “You can always go out in the parking lot and siphon a little”.  It was a joke.  Both he and my dad understood that.  You might not want to say that in an eastern Minnesota town.  There might be someone at the next table who overhears the conversation and reports you for stealing gas.  They believe in law and order.


My brother was driving around an iron range town on a Sunday afternoon.  Nobody was on the streets.  The whole town was at the park for an arts festival.  He happened to go a couple of blocks in the wrong direction on a one way street.  An old lady outside her house screamed frantically, “You’re going the wrong way!”


It has been a couple of days since I had the rock customers from Hell at my place.  The man was drunk and he and his wife were crazy and unreasonable, and not very good examples of anything except drunk and crazy.  But I did detect a tinge of eastern Minnesota in their behavior.  I’ve run into it before.  Usually the people come to their senses and we part with a handshake and a semblance of friendship.


The man said I was guilty of false advertising because my website showed items I didn’t have in my shop.  Actually, I did have the items or reasonable facsimiles…tucked here and there in boxes and corners in various buildings on the property.  When people treat me right, I invite them in the house, offer a cup of coffee or hot chocolate, and search for an item that might please them.  Sometimes I come up with something even better than they anticipated.  I’ve shown people how to saw rocks, or grind them.  i send people out to my shop to serve themselves.  Sometimes I find money on the counter and I don’t know where it came from.


In case those people are reading this, I’d like them to know that even big box stores have different merchandise on their website.  The local community center bought  pro basketball equipment from Walmart.  It had to be ordered.  It wasn’t available in the store.  And it’s silly to accuse a small, struggling, micro mini hole-in-the-wall business of false advertising.  You save that for a car manufacturer or a pharmaceutical company, some big outfit with a CEO who makes a zillion dollars a year.  


Most people from eastern or western Minnesota are fine folks.  They just have, in some instances, different ways.  In my years doing craft fairs, I sold a total of two items to obviously intoxicated customers.  Both were items that said “velkommen” on them, Norwegian for welcome.  Both customers were friendly drunks.


Posted by oh5/ojhoff at 9:24 AM CDT
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I really would appreciate if anyone reading this would take a look at my ebay listings.  My ebay name is ojhoff218 




Posted by oh5/ojhoff at 8:26 AM CDT
Updated: 03/03/15 9:01 AM CST
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older glaciation


Older glaciations in Minnesota either eroded away or are buried under later deposits.  It is hard to figure out what happened but a few conclusions have been drawn.  One is that the ice must have been very thick (at least a thousand meters).  Another is that, based on the number of wind-polished and faceted stone surfaces, dust bowl conditions worse than those of the 1930's once took place.

 Limestone and shale deposits from the Cretaceous lie under the younger drifts.  Some contain plant fragments carbon-dated to 40,000 years ago.  In some cases the sands and soils were subjected to intense chemical weathering so that even the toughest rocks became soft clay.  How long this takes to happen is debatable. 

Posted by oh5/ojhoff at 11:38 AM CDT
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More on Glaciers
I continue to read about glaciers in the Minnesota geology book.  The Laurentide Ice Sheet covered all of Minnesota except, perhaps, a small area in the southeast.  Tongues of ice extended into other states.  The center of the sheet was Hudson Bay.  It is possible to reconstruct the flow of glaciers by measuring the direction of striations and grooves and by tracking erratics back to their bedrocks.  Two troughs directed the course of ice streams from the glacier:  the Superior-Minneapolis and the Red River and Minnesota River.  These were straddled by higher, more erosion resistant rock types.  The troughs, on the other hand, were made up of more erodable materials.  Ice bulges developed at the perimeter and it's possible to study the advances and retreats of glaciers by studying the kinds of till left behind.  (There were also earlier glacial periods).  I think the Laurentide Ice Sheet deserves an in-depth study of its own.

Posted by oh5/ojhoff at 11:05 AM CDT
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 Since I was blogging about Minnesota geology and glaciers, I thought it might be appropriate to link to the website of my uncle the glaciologist.  His site has some amazing, and alarming, information that we all ought to be aware of.  In particular, this statement:  " The statement “glaciers are sensitive to the climate” was made countless times in published articles and the presentations we made throughout the 1960s-1970s, but little did we know just how sensitive they were. The now impending demise of many of them suggests glaciers are much more sensitive to the earth’s climate than are humans. We should have heeded their warning signals long ago. " 




Posted by oh5/ojhoff at 8:17 PM CDT
Updated: 03/25/14 8:27 PM CDT
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I was blogging about Minnesota geology (the glacier ages), but I also want to remind any readers, if there are readers of my blog, that I do have an ebay store. My ebay name is ojhoff218

Posted by oh5/ojhoff at 5:09 PM CDT
Updated: 03/17/14 5:12 PM CDT
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glacial theory

The glacial theory was first proposed by Swiss naturalist and teacher Louis Agassiz in 1837.  His idea that the earth had experienced very cold climates and an expansion of glacial ice explained erratic boulders and striated bedrock across Europe.  He came to the U.S. to teach at Harvard and found further evidence for his theories.  Earlier conclusions about the distribution of boulders attributed the phenomenon to the great flood.  A detailed reading of glaciation in Minnesota was started by N.H. Winchell, head of the newly created Minnesota Geological Survey, in 1872.  He was assisted by New England glacial geologist  Warren Upham.  Within 10 years they had completed a great deal of fieldwork mapping moraines and presenting an accurate view of the ice border in North America.  

Posted by oh5/ojhoff at 9:23 PM CST
Updated: 02/19/14 9:25 PM CST
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More About Glaciers



Glaciers shape the landscape by means of erosion, which manifests itself as abrasion and deposition.  Ice loaded with rocks and minerals slides along like coarse sandpaper.  Evidence on bedrock outcrops appear as scratches, or striations.  On a large scale the process is called quarrying or plucking.  Often tapered,  blunt nosed hills called whalebacks are formed.  Another result is the excavation of basins which become lakes.  Terms associated with deposition are till (unsorted debris), moraines (distinctive landforms), drumlins (streamlined hills with long axes parallel to the ice flow), kames (conical hills), and kettles (collapse pits formed when buried ice melts).  Belts of lakes also mark the extent of former glaciers.  


Posted by oh5/ojhoff at 7:21 PM CST
Updated: 02/15/14 7:51 PM CST
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 It's one of those long winter nights when Minnesotans ought to catch up on projects.  One of mine, long neglected, is blogging about MN geological history.  I couldn't remember where I left off so I looked it up.  I found the last topic I covered was the Cenozoic which brings us up to the Quaternary, 2 million years ago to the present.

 It's interesting.  The first few paragraphs describe erratics but do not mention them by name.  It talks about a 20 ton fine grained green-gray rock different than the pink granite bedrock upon which it rests on the floodplain of the Chippewa River.  Near the quartzite bedrock of Rock County are large granite fragments the Indians called the Three Maidens.  In Dakota County a granite boulder was honored by a continuous wash of red ochre, probably because it was obviously different than the bedrock.  This was long before European settlement.  These rocks were all carried by glaciers.  They are called erratics, which was the subject of my acrylic painting (of Finnish erratics) of which I am so proud to say was purchased by an employee of the Guggenheim and is displayed in her private gallery. 





Posted by oh5/ojhoff at 1:09 PM CST
Updated: 01/09/14 6:38 PM CST
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neglect, ebay, etc.
Yes I neglect this blog.  I also neglect my website.  Today I took tentative steps to set up a site, not a mirror site but an adjunct, that is more smart device friendly.  I'll keep this one as well.  Also, I sell on ebay.  Take a look at ojhoff218

Posted by oh5/ojhoff at 1:08 PM CDT
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One of the more interesting rock formations I sell in my shop is stromatolite, aka algae jasper.  A very popular source is the Mary Ellen mine, now underwater.  This past summer a customer took photos of the mine pit and and sent them to me.  I told him what I knew, that my family signed waivers to collect specimens so many years ago.  He happens to have the same surname as our MN U.S. senator and there IS a family connection.  Smile




Posted by oh5/ojhoff at 11:01 AM CDT
Updated: 09/30/13 2:08 PM CDT
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Gathering my thoughts.....
It has been ages since I posted here.  So much has happened.  I don't think I've ever mentioned that I am now selling Thunder Bay amethyst.  I sold a few small jewelry making samples on Ebay and one of my customers said they had gold and copper flecks all through them.  I've never seen the flecks but I researched the subject and it's a possiblity.  Other metals that might be present are silver, platinum, nickel, chalcopyrite, and bismuth.


Posted by oh5/ojhoff at 1:20 PM CDT
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