lablover2484
starting to shine!
Member since September 2008
Posts: 39
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Post by lablover2484 on Oct 8, 2008 10:09:33 GMT -5
I know this is probably a silly question, but reading alot of these postings kinda has me wondering. I know there is a different hardness to different rocks, but is there a list somewhere that tells you which ones are which? I am learning alot of the different kinds but the hardness is something I dont really know yet. And I really dont want to mess up anything that I have by rolling it with the wrong other rocks or the wrong grit. And also are you suppose to wash your final product with soap if so what kind is best? Can someone help me please!!!!!!!
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Oct 8, 2008 10:35:09 GMT -5
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Wolfden
fully equipped rock polisher
Member since November 2007
Posts: 1,368
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Post by Wolfden on Oct 8, 2008 10:59:50 GMT -5
I use Borax for a final wash the ol' 20 mule team lol
Dennis
p.s. thats a great chart ejs thanks
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pebblepup
has rocks in the head
Succor Creek Thunder Egg
Member since July 2008
Posts: 515
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Post by pebblepup on Oct 8, 2008 11:10:29 GMT -5
Here is a Mohs Hardness Scale that is used for determining mineral hardness.  A simple test you can do is to use known materials to scratch unknown materials. If the unknown material is scratched by the known material you know that the unknown material is softer than the known material. If the known material is scratched by the unknown material you now know the unknown material is harder. This technique can also be used to group stones that are close to the same hardness. |
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nansaidh
spending too much on rocks
Jewelry artist, graphic designer, dog lover, car nut (etc.)
Member since August 2008
Posts: 311
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Post by nansaidh on Oct 8, 2008 11:49:21 GMT -5
Wow, it sure is a nice chart - I hadn't seen that one. Thanks!
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Post by Noosh9057 on Oct 8, 2008 12:13:40 GMT -5
This is a great chart. I printed it out. Roger |
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lablover2484
starting to shine!
Member since September 2008
Posts: 39
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Post by lablover2484 on Oct 8, 2008 12:19:56 GMT -5
thank you for the chart it is very helpful. I printed it out and now I just have to learn it. lol Thanks a bunch
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Post by Hard Rock Cafe on Oct 8, 2008 12:35:08 GMT -5
Of course one of the challenges is that a rock can be composed of multiple minerals of varying hardness (e.g. granite). This often leads to the softer minerals wearing away faster than the hard ones (undercutting). So, it helps if the rock is a uniform material
It also helps to know that rocks by different names are all made of the same mineral (e.g. agate, bloodstone/heliotrope, carnelian, and chrysoprase, are all cryptocrystaline forms of quartz).
Since there is no scientific basis for rock names, it can be difficult to determine the hardness based on the name alone and the Mohs scale and method become all the more important. If the hardness test gives the same results for different rocks, you should be able to tumble them together.
Thanks for the chart ejs!
Hope that helps more than it hurts,
Chuck
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Oct 8, 2008 14:36:26 GMT -5
Lablover, regarding soap: Most people recommend Borax (the green box "20 Mule Team Borax" of powder that you can find in the supermarket soap aisle) or pure Ivory soap (the pure bars, not the box of powder which usually has colors/perfumes added) which I make by grating bars with a cheese grater. Most people say to use 1 TB in a 3# barrel for the rinse. Good luck!
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Post by connrock on Oct 8, 2008 15:05:33 GMT -5
When you are out collecting rocks keep a piece of jagged quartz in your pocket.
Try to scratch the rock (s) in question.If the quartz doesn't scratch the rock (s) then they are OK for you to keep.
It's a good rule of thumb and easy to take along.
connrock
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Post by Hard Rock Cafe on Oct 8, 2008 16:35:02 GMT -5
Good tip!  I normally carry a pocket knife, but a nail and a file are kind of a pain!  Chuck |
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Post by Condor on Oct 8, 2008 17:58:19 GMT -5
That's an excellent chart pebblepup. I'm going to use that with my middle school students when I do the rock cycle. Thanks for posting it. One question though. Is there a way to change the spelling of the word 'florite' to 'fluorite?' If not, I'll just redo the whole chart.
Condor
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Post by deb193redux on Oct 8, 2008 18:35:49 GMT -5
BUT - most of what tumbles well is in a small range of the chart. You ideally want a detailed listing of various obsidians, agates, and jaspers in the 5.5 to 7.5 range. You would also benefit form a column indicating shich will absorbe water and which will not.
Get a quartz crystal point. If it scratches anything too easily, than it cannot be tumbled, or should be tumbled by itself.
Can also get a piece of obsidian or serpentine, and if one of those scratches a rock, than I would not tumble the rock.
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Post by Hard Rock Cafe on Oct 9, 2008 8:47:32 GMT -5
Good point Dan. There is a lot of rock that will never polish in a tumbler because it is too soft; it will just grind away into muck.
Of course, I'm using that to my advantage with the Thomsonites. The basalt is softer than the Thomsonites, so I'm tumbling the basalt away.
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randy
starting to spend too much on rocks
Member since August 2008
Posts: 117
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Post by randy on Oct 9, 2008 23:16:28 GMT -5
ejs,
Thanks for the link. I found that list really helpful. I have it bookmarked now!
Randy
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Post by Hard Rock Cafe on Oct 10, 2008 8:35:39 GMT -5
I was looking for online sources of quartz points yesterday. As luck would have it, my daughter brought home a quartz point from elementary school yesterday and gave it to me (along with 1/3 geode and a small piece of pyrite? crystals that looks like squared off stacked Cs; I know I've seen pictures of this form before, but can't remember what it is). Anyway, one of those fun/funny coincidences of life...
Chuck
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DeanW
has rocks in the head
Member since December 2007
Posts: 721
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Post by DeanW on Oct 10, 2008 21:48:37 GMT -5
Another tool to help ID hardness is an ALUMINUM (typically roofing) nail. If it can scratch the rock, then probably too soft. This is often used in central California to differentiate Jade (harder, won't scratch) from Serpentine (scratches).
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