Site hosted by Build your free website today!

Rocks In My Head

Blog Tools
Edit your Blog
Build a Blog
RSS Feed
View Profile
« April 2011 »
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
Entries by Topic
All topics  «
geology et al
some days are pretty good
My own link
Rock Shop
You are not logged in. Log in
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
Post Comment | Permalink | Share This Post

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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post

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
Post Comment | Permalink | Share This Post

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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post
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
Post Comment | Permalink | Share This Post
my shop

My shop still exists both online and in real space but I am not in a mood to blog about mineralogy, paleontology, geology, metaphysics, stone healing, or anything like that.  Two events have happened that have ground my business to a halt.  It was barely chugging along as it was.  I really can't afford to replace the road signs that were taken down.  But even if I do, my inventory is mediocre, leading me to ask myself, why replace the signs?  My cash flow problem prevents me from purchasing fill-in inventory for making my shop look more inviting and colorful and interesting.  There are other ways to obtain inventory.  Self collecting in the field.  Trading with someone who stops in, or by mail.  Processing raw materials on hand to make something new and different.  None of these are as easy as putting in an order.

I have a pile of rocks that I can't do much with, so little by little I am painting on them.  A native American artist stopped in the other day.  He makes sculptures out of rock of all sizes from boulders to small hand sized pieces.  I might not be able to do that but maybe I can make something.

Posted by oh5/ojhoff at 8:54 PM CDT
Post Comment | Permalink | Share This Post
I think I will blog now and then about rocks as opposed to minerals.  Rocks are aggregates of minerals, classified according to how they were formed (igneous, sedimentary, metamorphic).  These can be subdivided into other classifications, such as particle size.  Formation of rocks is a gradual process and one type sort of morphs into another.  Selecting reference points is  arbitrary; however, it has been done and there are a finite number of rock types, according to petrologists.  Usually in books, igneous rocks are considered first.  The first one on that list is andesite, named for the Andes mountains.  It is an intermediate crystalline rock, consisting mainly of plagioclase feldspar.  There is also a mineral called andesite, which confuses matters.

Posted by oh5/ojhoff at 2:37 PM CDT
Post Comment | Permalink | Share This Post
Minnesota precambrian
Ok, now I'm blogging about Minnesota geology.  There is an ongoing search for the original granitic crust, which is elusive.  It is possible it doesn't exist anymore.  It may have been eroded and recycled.  It's also possible that the original crust was basaltic.  One of the difficulties is that most of Minnesota is covered with glacial drift. The Canadian shield contains many belts of volcanic and  sedimentary rock.  It has been suggested that the belts are the uplifted remnants of the "basement", the structure upon which the volcanic-sedimentary features were built.  But that doesn't mean they are the original crust.
It is likely that the very early days of Minnesota were ones of violent volcanic activit

Posted by oh5/ojhoff at 8:26 AM CDT
Post Comment | Permalink | Share This Post
chromates and so on

Chromates are a source of chromium for electroplating steel, and are also used to make stainless steel.  The most popular is crocoite which forms bright, attractive crystals of red, yellow and orange.  Unlike tarapacaite and lopezite, crocoite is not soluble in water.  

Tungstates and molybdates are always associated.  They are important to industry as filaments in bulbs and tubes, and useful in nuclear reactors, to clad fuel rods.  There are three main groups:  wolframite, scheelite, and wulfenite.  The only one that I am personally familiar with as a mineral is wulfenite.  

I am finished with mineralogy for a long while.

Posted by oh5/ojhoff at 10:43 PM CDT
Updated: 03/19/10 11:05 PM CDT
Post Comment | Permalink | Share This Post
pyromorphite and others

Pyromorphite is a pseudomorph after galena and cerussite and takes the form of these minerals which it replaces.  It is found in association with lead. 

The phosphate called vanadinite is formed by water which alters the lead ore.  I do have a very nice sample of this somewhere in my collection.  The crystals can be many colors, usually a cinnamon brown.  As far as lead is concerned, vanadinite can be found in commercially viable amounts.  Torbernite is hydrous copper uranium phosphate, and autunite is hydrous calcium uranium phosphate.  The two occur together.  Torberite is bright green.  Autunite is greenish or yellowish and is vividly fluorescent.  

And so I've come to the end of the phosphates.  Next I will dispose of the chromates.  When will I get around to collecting all of these?  Should I blog about rocks next, as opposed to minerals?

Posted by oh5/ojhoff at 8:22 PM CST
Updated: 03/19/10 11:06 PM CDT
Post Comment | Permalink | Share This Post

Newer | Latest | Older