Mohs scale of hardness can kick the bucket.
Autymn D. C.
Vickers/Brinell/Knoop/Berkovich, with Mohs (or Werner: "MOHS' OR
WERNER'S HARDNESS SCALE: WHO SHOULD GET THE CREDIT?,
http://gsa.confex.com/gsa/2003AM/finalprogram/abstract_60785.htm.), a
nasty roadblock is soon found at the metals and other softer
elements. One can look at Wikipedia, Webelements, any metal supplier,
or any primary text (Webelements's 1960s tome) or secondary (/CRC
Handbook of Chemistry/--funny, it doesn't fit in a hand anymore..) to
see these materials slip out of alignment somewhere under quartz.
It's somewhat hard to find absolute hardnesses for the ten minerals to
fit every other thing along, even on the web, but they should be from
a experiment for that very purpose rather than a casual list on
someone's website which more likely gets them from several persons and
tests.
On the relative scale, there should be emfasis on the "mineral", as
these tests are in normal settings and for raw or natural materials,
rather than perfect, lab-grown, summetric models. So metals will come
with a oxide film which blow up their hardness inside, as elèctronic
pools make for soft atoms. Absolute hardness tests indent with a hard
spike a good way, rather than scrape or nick one mostly-flat surface
against another. Also, at the soft end the hardnesses crunch together
to make precise readings awkward. Relative tests can't use the same
indenter; they go up and down the list--and at the soft end there's
more likely mutual scratching. This is why each slot on Mohs's is
about a factor of two: http://wikipedia.org/wiki/Mohs_hardness.
If two materials had the same hardness, they would scratch each other;
if flat, they would push and give way the same. So don't use a
scratcher or indenter the same stuff, shape, and size as your target.
This is something of a collisional or dunamic effect, where the same
materials match impedanse to be resonant [in]deformers. This is why
self-tests for diamonds can yield inflated hardnesses, about twofold
of their "real". When minerals on a scale differ twofold, then a
target's share of the brunt is two-thirds; there'll always be slack in
imperfect, noninfinitely-stiff spikes. Another way to blow up
relative hardness is if the scratch doesn't take, if the brunt is a
fraction of whitever the indenter would hit as its target is always
fast and steady; this would be a function of lubricity (as in
http://google.com/groups?q=electrium-grafite). If you want a freaky
"hard" art, one thas looks harder than say corundum or diamond, then
you could sputter a tough material lik moissanite, sillimanite,
hercynite, or elpasolite (or, for you, sialon) with a slippery one--a
grafitoid boride, sulfide, or borazon. Nature doesn't get a glassier
treatment. And maybe with one of these, borane rockets can come
back...
Nature works on minerals--casts, churns, kneads them; so their
hardness you see published is useles if you want their ultimate
property. With all of the factors above, the Mohs scale is riddled
with junk. They say wüstite is 5.5--which would be between 5·5 and 7
GPa--but find its Vickers and it'll be 3 GPa, which is about 4.5.
Almost every elemental metal has this lameness. Mohs is useful if you
find them off rock, and if you habitually rub stuff against them next
in hardness on-list, as those listmarkers [which none own] are good
for such rubbing and nothing else.
So what I did was build a list of the most important materials, out of
two much-greater lists in my notes (My first list of hardnesses is
still on my old computer, and I couldn't recover as the monitor was
dead. All of my lists go beyond the CRC's wimpy ceramics'
hardnesses. The first list had over a screenfull of "steels", tool
steels, but then I gave up as there were too many.), under both scales
but then recalibratd the relative scale by the absolute scale. I took
care to get extrema of each material as material, so no raw or cast
(pollacrustallic--where polla- is mani- and polu- is much-, and
crustallic is.. froxty) data where I could; oftentimes I took the
softest and hardest whole data.
-Aut
Neat Stuff and meath
"My hardness scale is 7M=7H:=12GPa-standard, and natural logarithmic."
WM 2fullerite:310,290FGPa
E.5 2carbium: '231'; TH=240
EM carbium:167,137FGPa->9.5H; nc-glassy carbium
T+ nc ;osbornite-glassy ;nierite-titanium disilenylide:130,100
TM diamond:115VGPa->9.2H
9.8 ;carbazon:92->9H=89
9.5 alkynylane:90,40; g. diamond,B4C:70; g. ;osbornite,g. ;borazon:80
9.4 ::BC2N:'62'; ;CN:'62.3'; ::BC4N:'68'
9.3 glassy B:'49'; ;rhenium diboride:'48'; ;seifertite*or
9.2 ;borazon: '45'; metagrafite*mor:'35'; g. ;SiC,g. ;WC:40;
g. ;chromia:36
9.1 ;nierite:'35'; ;moissanite:'32·6'->8H,'30','27.4'; stishovite*tt:
31·8,26·2
9+ ;corundum:30·7,'27',26; ;B4C: 25; boron:25.3; glassy ;zirconia:>28
9M ;corundum [wet?]:'20'VGPa; glassy Cr:21·6; g. W:
23; ;osbornite:'24·5'
8M :topaz:'18'VGPa; :beryl; ;coesite*m:'17'; glassy silica:24-5
7.7 ;chromia,hafnia:'16'
7.5 ;zirconia,glassy Si:'15';
7.3 :spinel,bromellite:'14'; glassy ;cementite
7M=>7H ;quartz*xr:'12'VGPa; :::clinozoisite*m
6.9 ;cementite:11·4; tungsten carbide:'11'; :fayalite
6.7 glassy Os:>10·6; ;hematite:'10·5'
6.6 silicon,glassy Fe,;thoria[nite]:'10'
6.5 ;rutile:
9·7,9·65,9·65; ::garnets; :::feldspars; :::zoisite*or; :::Metglas
6M ::orthoclase:6·9VGPa->7·0; ;ceria; ;moganite*dm; glassy Ti,g.
titania
5M ::apatite:5·4VGPa->;uraninite:'5·5'; ::gleass; ::::mesolite
4.8 glassy Au:5
4.7=>6H=4·4
4.5 glassy Cu:3·6; alloy ;steels
4.4 tungsten:'3·43'
4.3 osmium:'3'VGPa; glassy Ag; ;wüstite:'3·1'; glassy ;fluorite:3·15
4.1 glassy grafite:2·4; ;pearlite:'2·4'
4M ;fluorite:2·0VGPa; ;cuprite; wrouht iron
3.5 :aragonite*or; ;lime; beryllium,glassy Al:1·7; hafnium:'1·76'
3M :calcite*dtr:1·5VGPa->5H=1·6
2.5 chromium:'1·06'; titanium,glassy Mg,;steel,:amalgam:'1';
zirconium:'·9'
2M=>4H ::gypsum:·6VGPa; iron:·6; sulfur
1.7 ::gaolinite*tx; ;salt:'·45'';
grafite*dx:·5,·25; :moschellandsbergite:·5
1.5 copper:'·37'
1.2 silver,magnesium:'·25'->3H=·22; gold:'·216'
1M ::talc:·15VGPa; aluminium:'·167'; ::natron; ::nacrite*dm
0.6=>2H=·08 :::ethylmethamite,::polycarbonate,::::horn:'·1'
0.2 tin:'·05'; lead:'·04'; :ethine,::sap,:::shell:·04-·08
0M ;ise:·025,·02VGPa; 1H=·03 ::::leoss
=>0H=·01 ::hardwood; :::weax
(.: "dot" or "ah"; ·: "mot" or "uh", shwah)
the paper, one! result: http://google.com/search?q=Mohs+Vickers+hardness+quartz+12.2-GPa
"EFFECTS OF WATER DESORPTION ON INDENTATION MICROHARDNESS ANISOTROPY
IN MINERALS". THE AMERICAN MINERALOGIST, VOL..53, NOVEMBER DECEMBER,
1968.
http://minsocam.org/ammin/AM53/AM53_1899.pdf
meta...@hotmail.com
> If/When one tries to concordify the absolute hardness scales, such as
> Vickers/Brinell/Knoop/Berkovich, with Mohs (or Werner: "MOHS' OR
> nasty roadblock is soon found at the metals and other softer
> elements.
Snip
What you are fumbling with has already been done better for metallic
materials. Go to Google books and look up pages 115 and 116 of the
book "Materials: Engineering, Science, Processing and Design" by
Michael Ashby, Hugh Shercliff, and David Cebon. Figure 6.5 on page
116 is a chart showing the relation between the Rockwell A (HRA),
Rockwell C (HRC), Brinell (HBW), Vickers (HV), and Mohs scales.
As an additional bonus Ashby et al also show a scale for average yield
strength. Hardness tests (which are almost nondestructive) often are
used as tool in quality control of metal products.
Pittsburgh Pete
DISCLAIMER
We do not believe what we write, and neither should you. Information
furnished to you is for topical (external) use only. This information
may not be worth any more than either a groundhog turd, or what you
paid for it (nothing). The author may not even have been either sane
or sober when he wrote it down. Do not worry, be happy.
Autymn D. C.
> What you are fumbling with has already been done better for metallic
> materials. Go to Google books and look up pages 115 and 116 of the
> book "Materials: Engineering, Science, Processing and Design" by
> Michael Ashby, Hugh Shercliff, and David Cebon. Figure 6.5 on page
> 116 is a chart showing the relation between the Rockwell A (HRA),
> Rockwell C (HRC), Brinell (HBW), Vickers (HV), and Mohs scales.
Do you own this book? 116-117 aren't in the preview; I can't see the
chart. And the lone torrent with this book is over a gigabyte of
other books. How is this "better"? I know about efunda.com's
convertor (Clear your cookies after the trial.), which is inconsistent
with Mohs. There's another site with a chart between the Shores,
Rockwell, and Brinell--which is a good calibrator for the organic
plastic end. If efunda and /Materials/ use the same refs, or if they
use the same ref as WebElements, then their conversions are trash.
Whose work is /Materials/'s chart?
And as my calibrator is a paper which gets rare mention, I doubt the
chart is better than mine--which is more comprehensive than any other
book's.
> As an additional bonus Ashby et al also show a scale for average yield
> strength. Hardness tests (which are almost nondestructive) often are
> used as tool in quality control of metal products.
so..?
meta...@hotmail.com
> On Apr 5, 9:13 am, metale...@hotmail.com wrote:
>
> > What you are fumbling with has already been done better for metallic
> > materials. Go to Google books and look up pages 115 and 116 of the
> > book "Materials: Engineering, Science, Processing and Design" by
> > Michael Ashby, Hugh Shercliff, and David Cebon. Figure 6.5 on page
> > 116 is a chart showing the relation between the Rockwell A (HRA),
> > Rockwell C (HRC), Brinell (HBW), Vickers (HV), and Mohs scales.
>
> Do you own this book? 116-117 aren't in the preview; I can't see the
> chart. And the lone torrent with this book is over a gigabyte of
> other books. How is this "better"? I know about efunda.com's
> convertor (Clear your cookies after the trial.), which is inconsistent
> with Mohs. There's another site with a chart between the Shores,
> Rockwell, and Brinell--which is a good calibrator for the organic
> plastic end. If efunda and /Materials/ use the same refs, or if they
> use the same ref as WebElements, then their conversions are trash.
> Whose work is /Materials/'s chart?
I already told you where it is, but now I will also tell you how to
get there.
Just go to Google book search and put the words:
mohs hardness asby
into the search box. Figure 6.5 from Ashby, Shercliff & Cebon should
pop right up.
Since this is a book written for undergraduates they do not bother to
reference how they got the Mohs hardness conversion. I do not know
where they got this chart from.
I am not your librarian. If you want to find this book then I suggest
that you take your tired fingers off the keyboard, shut off the
monitor, and take a trip down to your friendly local engineering
library. Not everything is out there for free on the Internet. You can
go to open WorldCat and find out what libraries have the book though.
http://worldcat.org/
A Shore (Durometer) hardness test (A and D) on a rubbery material
measures elastic behavior (modulus of elasticity) rather than plastic
deformation (like Rockwell or Brinell hardness), so attempts at
conversion are not likely to be very useful.
Pittsburgh Pete
Aidan Karley
d2ea0c...@a9g2000prl.googlegroups.com>, wrote:
> You can
> go to open WorldCat and find out what libraries have the book though.
> http://worldcat.org/
>
down the road ... and the site tells me there are 3 copies in the UK,
but none in Scotland. Looks like they don't cover Aberdeen (2
universities and 3 other major libraries). Or Edinburgh (4 university-
grade institutions and I-don't-know-how-many research libraries). But
they do cover Glasgow (2+ university-grade institutions and I-still-
don't-know-how-many research libraries).
Strange range of coverage, but probably worth a bookmark anyway.
It seems to me that Mr Autymn has forgotten the main point of
Moh's scale : it was defined with minerals that were reasonably easy to
get samples of, in good purity, so that a geologist could simply read
the descriptions of the minerals, and go out and acquire a set of
reference materials with the precision controlled by nature. It doesn't
depend on the distribution of engineering materials, precise
measurement, etc - it's by design a field technique.
Describing a Moh's hardness more accurately than +/- about a
quarter of a point is spurious accuracy. In particular, you've got to
start to define crystallographic orientation if you're working at such
precision.
Remember Kyanite - a.k.a. Disthene. Di = two ; sthenos =
strength. "Two strengths" : Mohs 5½ on one axis and 6½-7 on another.
And you can demonstrate it on a crystal of only a few mm.
--
Aidan Karley, FGS,
Aberdeen, Scotland
meta...@hotmail.com
wrote:
Aidan:
Worldcat is a very well known “union catalog” that combines the
catalogs of its member libraries. For many years it was a tool only
used by reference librarians. Worldcat is a wonderful resource for
locating obscure books. A less than precisely focused Worldcat search
will bury the user in a gigantic flood of results.
It comes from OCLC. The name Worldcat is quite old and reflects their
hopes for creating a truly planetary catalog. Right now the name is
another example of the American fallacy that the US is the same as the
world (just like the national baseball championship is misnamed the
World Series). Worldcat is rather comprehensive for the US because it
started in Dublin (Ohio, not Ireland). It does include the British
Library though.
Apparently many of the Scottish libraries you use have not joined OCLC
and Worldcat. A quick Google search found a Scottish union catalog
called CAIRNS that may be more useful for you. http://cairns.lib.strath.ac.uk/
Pittsburgh Pete
meta...@hotmail.com
wrote:
> In article <ff459e93-99fd-409e-8d5d-d2ea0c90b...@a9g2000prl.googlegroups.com>, wrote:
SNIP
>
> It seems to me that Mr Autymn has forgotten the main point of
> Moh's scale : it was defined with minerals that were reasonably easy to
> get samples of, in good purity, so that a geologist could simply read
> the descriptions of the minerals, and go out and acquire a set of
> reference materials with the precision controlled by nature. It doesn't
> depend on the distribution of engineering materials, precise
> measurement, etc - it's by design a field technique.
> Describing a Moh's hardness more accurately than +/- about a
> quarter of a point is spurious accuracy. In particular, you've got to
> start to define crystallographic orientation if you're working at such
> precision.
> Remember Kyanite - a.k.a. Disthene. Di = two ; sthenos =
> strength. "Two strengths" : Mohs 5½ on one axis and 6½-7 on another.
> And you can demonstrate it on a crystal of only a few mm.
>
> --
> Aidan Karley, FGS,
> Aberdeen, Scotland
Aidan (and Autymn):
There is an article by Ulrich Burchard in The Mineralogical Record
(Volume 35, March-April 2004, pages 109 to 120) entitled “The
Sclerometer and the Determination of the Hardness of Minerals” which
discusses the problem of anisotropy and also mentions kyanite.
Of more interest to the main point of this thread is that Figure 2 of
the article plots a smooth line correlating between Mohs hardness and
Vickers indentation hardness for 14 minerals ranging from talc to
diamond. The text says this comes from the original 1925 Vickers work
on that indentation hardness test method, but the detailed reference
is not given in the bibliography.
Figure 12 of the article shows a photograph of a Durimet microhardness
tester. In the US this was sold as the Leitz Miniload. It was a rugged
and reliable instrument, but with a mediocre illumination system
typical of the pre-1970s testers. Anyone who has used the newer
testers does not want to go back to a Miniload.
Pittsburgh Pete
meta...@hotmail.com
> If/When one tries to concordify the absolute hardness scales, such as
> Vickers/Brinell/Knoop/Berkovich, with Mohs (or Werner: "MOHS' OR
> nasty roadblock is soon found at the metals and other softer
> elements.
snip
The topic of making an absolute hardness scale somewhat equivalent to
the relative Mohs scale apparently has a long history (particularly in
the Russian ceramics literature). Since I don’t read Russian most of
it is inaccessible to me.
However, there is an English translation of a Polish book by Andrzej
and Janusz Szymanski titled “Hardness estimation of minerals, rocks
and ceramic materials” from back in 1989. (The Polish original is from
1976). Section 4.2 of this book (page 41) discusses comparative
empirical scales. Back in 1963 in a book on hardness of minerals A. S.
Povarennykh came up with an extended Mohs hardness scale running from
1 for talc to 15 for diamond. His work was in turn based on earlier
work by M. M. Khrushchev from back in 1950. Table 4.2.2 (page 46) of
the Szymanski’s book shows the relation between the extended scales
and the Vickers hardness scale. Povarennykh took crystallographic
orientation into account.
Pittsburgh Pete
meta...@hotmail.com
> Vickers/Brinell/Knoop/Berkovich, with Mohs (or Werner: "MOHS' OR
> nasty roadblock is soon found at the metals and other softer
> elements.
SNIP
>
> So what I did was build a list of the most important materials, out of
> two much-greater lists in my notes (My first list of hardnesses is
> still on my old computer, and I couldn't recover as the monitor was
> dead. All of my lists go beyond the CRC's wimpy ceramics'
> hardnesses. The first list had over a screenfull of "steels", tool
> steels, but then I gave up as there were too many.), under both scales
> but then recalibratd the relative scale by the absolute scale. I took
> care to get extrema of each material as material, so no raw or cast
> (pollacrustallic--where polla- is mani- and polu- is much-, and
> crustallic is.. froxty) data where I could; oftentimes I took the
> softest and hardest whole data.
>
> -Aut
SNIP
Andrzej and Janusz Szymanski wrote a book titled “Hardness estimation
of minerals, rocks and ceramic materials” back in 1989. (The Polish
original is from 1976). Section 4.2 of this book (page 41) discusses
comparative empirical scales. Back in 1963 in a book on hardness of
minerals A. S. Povarennykh came up with an extended Mohs hardness
scale running from 1 for talc to 15 for diamond. His work was in turn
based on earlier work by M. M. Khrushchev from back in 1950. Table
4.2.2 (page 46) of the Szymanski’s book shows the relation between the
extended scales and the Vickers hardness scale. Povarennykh also took
crystallographic orientation into account and changed some of the
minerals used for comparisons.
You may not have access to this book.
Part of Table 4.2.2 from Szymanski and Szymanski follows. It shows how
the 1950 Khrushchev paper relates the Vickers hardness (HV, in the
traditional units of kgf/(mm^2)) to the hardness class or degree (what
I’ll call the Extended Mohs hardness, or EMH) by a very simple
equation:
EMH = 0.7 * cuberoot(HV).
EMH Mineral HV range
1 talc 2.4 to 11
2 gypsum 36 to 90
3 calcite 105 to 172
4 fluorite 164 to 260
5 apatite 536 to 690
6 orthoclase 714 to 850
7 quartz 1000 to 1460
8 topaz 1427 to 1800
9 corundum 2050 to 2200
10 titanium carbide 2850 to 3200
11 boron 3400 to 4000
12 boron carbide B4C 4950
13 boron carbide B6.5C 5600 to 5800
14 diamond carbonado ?
15 diamond bort
10060
Also, in the Appendix to this book they tabulate hardness values for
most solid elements (Table I) and a lot of minerals (Table II).
How is your scale (shown without an explicit equation) a major
improvement over what was published in this 1989 book?
Pittsburgh Pete
Ed
> If/When one tries to concordify the absolute hardness scales, such as
> Vickers/Brinell/Knoop/Berkovich, with Mohs (or Werner: "MOHS' OR
> "hard" art, one thas looks harder than say corundum or diamond, then
> you could sputter a tough material lik moissanite, sillimanite,
> hercynite, or elpasolite (or, for you, sialon) with a slippery one--a
> grafitoid boride, sulfide, or borazon. Nature doesn't get a glassier
> treatment. And maybe with one of these, borane rockets can come
The Mohs hardness scale represents Ordinal data - the metallurgical
(HRC, HB, KV, HV etc) and nonmetallic (shore) hardness scales are
assumed as interval scales - but are most likley not at their
extremes: NOTE there is no "0" i.e. "zero" Vickers, HB, HRC etc
hardness measurement.
Correlation is performed best on ratio data with the aim of getting a
useful a conversion that MAY be useful in some practical cases.
Correlation using ordinal data is an incorrect application (The
"hammer-nail" problem) of a limited tool.
The closer you look the more dispersed the truth gets.
Ed
Martin H. Eastburn
It wasn't a metal scale in the first place. It was for minerals
and was handy for other uses. I always had a small test kit
with me when hiking. (My Minor is in: Geology, Stratigraphy)
If you look at the first web site - the absolute values
are wide scales. Useful in minerals but not life in general.
http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness
http://en.wikipedia.org/wiki/Friedrich_Mohs
Notice the subject that Friedrich had when he invented the scale.
Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/
----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.pronews.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= - Total Privacy via Encryption =---
alv...@example.com
> Ed wrote: <snip>
>> "MOHS' OR WERNER'S HARDNESS SCALE: WHO SHOULD GET THE CREDIT?
>
> Let the usage by metal users go and stop using Mohs Scale.
> It wasn't a metal scale in the first place.
> http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness
Notice the line where it says a file is 6.5 but the table just
below it says steel can be "8". Off hand, a file is the hardest
piece of steel that is "common". ~67hrc from my testing.
The table looks right to me in the area around glass and quartz
since some of my heat and cold treated knife blades can scratch
glass. ~66hrc (1095, 50100-B and even 8670-M)
http://en.wikipedia.org/wiki/Novaculite
Is there anything in an "Arkansas stone" (Novaculite) that's harder
than quartz crystals?
> http://en.wikipedia.org/wiki/Friedrich_Mohs
> Notice the subject that Friedrich had when he invented the scale.
> Martin H. Eastburn
Alvin in AZ
the wharf rat
>In sci.engr.metallurgy Martin H. Eastburn wrote:
>
>Is there anything in an "Arkansas stone" (Novaculite) that's harder
>than quartz crystals?
>
AFAIK novaculite *is* a form of quartz, it's a sedimentary rock made of very fine quartz
crystals...
Martin H. Eastburn
natural ones collected and shaped for the shop.
A extremely fine grain metamorphic rock typically with brown bands or cast.
The color indicates another material is mixed in the quartz. Perhaps topaz
or diamond. Arkansas is host to diamond fields. My bet is on other minerals
mixing in as in the painted desert and being of fine nature.
Might be chrome oxides as well.
I'll look in my Geo books more for this topic - rather - oh - a book!
Mineral facts and problems : Dept of the Interior Bulletin 630 Bureau of Mines:
"Sandstones are composed of quartz grains cemented with calcium carbonate, iron
oxide, clay, feldspar, or silica."
Knowing Arkansas a little - Aluminum is possible and the oxides are tough.
Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/
Timberwoof
> In sci.engr.metallurgy Martin H. Eastburn wrote:
> > Ed wrote: <snip>
> >> "MOHS' OR WERNER'S HARDNESS SCALE: WHO SHOULD GET THE CREDIT?
> >> http://gsa.confex.com/gsa/2003AM/finalprogram/abstract_60785.htm
> >
> > Let the usage by metal users go and stop using Mohs Scale.
> > It wasn't a metal scale in the first place.
Why is this thread titled "kicks the bucket"?
Given that it's about rocks, shouldn't it be "bites the dust"?
--
Timberwoof <me at timberwoof dot com> http://www.timberwoof.com
"When you post sewage, don't blame others for
emptying chamber pots in your direction." ‹Chris L.
meta...@hotmail.com
Alvin:
If you look around on Google you will find reference to a book called
“Industrial Minerals & Rocks: Commodities, Markets, and Uses”, 7th
edition.
If you look at the preview in Google Books you will find that on page
153 of the chapter on abrasives it notes that:
“Natural abrasive stones are made from a wide variety of materials
including sandstone, novaculite…The superior cutting quality of some
of these stones is due to the well-disseminated, fine-grained
inclusions of garnet or other minerals of superior hardness.’
It doesn’t specifically mention garnet earlier in a discussion of
novaculite where it notes that material is primarily quartz.
Pittsburgh Pete
Martin H. Eastburn
since there are better scales.
Still used with stones.
Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/
Timberwoof wrote:
> In article <g0i79k$d8r$1...@reader2.panix.com>, alv...@Example.com wrote:
>
>> In sci.engr.metallurgy Martin H. Eastburn wrote:
>>> Ed wrote: <snip>
>>>> "MOHS' OR WERNER'S HARDNESS SCALE: WHO SHOULD GET THE CREDIT?
>>>> http://gsa.confex.com/gsa/2003AM/finalprogram/abstract_60785.htm
>>> Let the usage by metal users go and stop using Mohs Scale.
>>> It wasn't a metal scale in the first place.
>
>
> Why is this thread titled "kicks the bucket"?
>
> Given that it's about rocks, shouldn't it be "bites the dust"?
>
meta...@hotmail.com
>
> - Show quoted text -
Ed:
You are right that adjusting the entire scale isn’t a correct
application. What should be done is to pin the conversion down by only
using the ten minerals that define the Mohs scale.
I had expected that you would object that measuring scratching like
Mohs simply is a different type of measurement that an indentation
test. The metals analog to scratch hardness is file hardness.
In industry the somewhat academic distinction between ordinal and
interval data is just plain ignored. Out on the shop floor people are
quite happy to check approximate Rockwell C hardness of steel products
by testing using files. SAE even has a standard for this, J864 on
Surface hardness testing with files. As with the Moh’s scale their set
of hardnesses aren’t evenly spaced – the five values in J864 are 50,
55, 58, 62, and 65 HRC.
You can also buy hardness testing files in sets of six, with evenly
spaced values at increments of 5 HRC from 40 to 65. McMaster Carr
still has them in their big yellow wholesale hardware catalog.
Pittsburgh Pete