Physical properties of jade?

[David Prokopetz]

Hi.

I have a question about the properties of jade. While perusing a text on
Chinese history, I came upon a claim that jade is "stronger than steel", and
that its utility in manufacturing tools and weapons was limited only by the
rarity of large, unflawed pieces to work with. This struck me as an odd
assertion, and I decided to follow up on it; I found it to be repeated in
several books on mineralogy I have on hand, including one which more
specifically states that "fine-grained jadeite [...] has greater tensile
strength than steel".

However, I'm not able to find any actual data to back this up; all the
sources I've checked list jadeite's *hardness* (which does indeed compare
favorably to that of hardened steel, both ~7 on Moh's scale), but none have
numerical data on jadeite's toughness, tensile strength, or anything else
that would allow a more comprehensive comparison. Does anyone know of a
source that contains the information I'm looking for - or, better yet, an
actual comparative study?

(Though I realise the latter is probably too much to hope for...)

Thanks,

- David Prokopetz.

[stan]

Not quite what you are looking for, but I have a 75 pound piece of fine
grained jade from Canada, and we used a large diamond saw to cut small part
of it, and it did dull the saw substantially, water cooled too.

Post by David Prokopetz
Hi.
I have a question about the properties of jade. While perusing a text on
Chinese history, I came upon a claim that jade is "stronger than steel", and
that its utility in manufacturing tools and weapons was limited only by the
rarity of large, unflawed pieces to work with. This struck me as an odd
assertion, and I decided to follow up on it; I found it to be repeated in
several books on mineralogy I have on hand, including one which more
specifically states that "fine-grained jadeite [...] has greater tensile
strength than steel".
However, I'm not able to find any actual data to back this up; all the
sources I've checked list jadeite's *hardness* (which does indeed compare
favorably to that of hardened steel, both ~7 on Moh's scale), but none have
numerical data on jadeite's toughness, tensile strength, or anything else
that would allow a more comprehensive comparison. Does anyone know of a
source that contains the information I'm looking for - or, better yet, an
actual comparative study?
(Though I realise the latter is probably too much to hope for...)
Thanks,
- David Prokopetz.

[Carl 1 Lucky Texan]

You could dig around at www.gemsociety.org , www.rockhounds.com and
www.yourgemologist.com (even post questions to the lapidary Arts Digest
- http://www.gemcutters.org/subscribe.htm) as well as looking for books
and organizations (I THINK there is a jade specific gem&mineral society
in California). a Coulpe of things I'd like to mention, jade was used as
anivils for metalworking. Also, few other materials could be carved in
as thin/delicate forms as jade is often. While not technical, there is a
fantastic, not-to-be-missed book called The Stone of Heaven for those
interested in jadeite's interesting history.

Carl
1 Lucky Texan

Post by David Prokopetz
Hi.
I have a question about the properties of jade. While perusing a text on
Chinese history, I came upon a claim that jade is "stronger than steel", and
that its utility in manufacturing tools and weapons was limited only by the
rarity of large, unflawed pieces to work with. This struck me as an odd
assertion, and I decided to follow up on it; I found it to be repeated in
several books on mineralogy I have on hand, including one which more
specifically states that "fine-grained jadeite [...] has greater tensile
strength than steel".
However, I'm not able to find any actual data to back this up; all the
sources I've checked list jadeite's *hardness* (which does indeed compare
favorably to that of hardened steel, both ~7 on Moh's scale), but none have
numerical data on jadeite's toughness, tensile strength, or anything else
that would allow a more comprehensive comparison. Does anyone know of a
source that contains the information I'm looking for - or, better yet, an
actual comparative study?
(Though I realise the latter is probably too much to hope for...)
Thanks,
- David Prokopetz.

[George]

Post by David Prokopetz
Hi.
I have a question about the properties of jade. While perusing a text on
Chinese history, I came upon a claim that jade is "stronger than steel", and
that its utility in manufacturing tools and weapons was limited only by the
rarity of large, unflawed pieces to work with. This struck me as an odd
assertion, and I decided to follow up on it; I found it to be repeated in
several books on mineralogy I have on hand, including one which more
specifically states that "fine-grained jadeite [...] has greater tensile
strength than steel".
However, I'm not able to find any actual data to back this up; all the
sources I've checked list jadeite's *hardness* (which does indeed compare
favorably to that of hardened steel, both ~7 on Moh's scale), but none have
numerical data on jadeite's toughness, tensile strength, or anything else
that would allow a more comprehensive comparison. Does anyone know of a
source that contains the information I'm looking for - or, better yet, an
actual comparative study?
(Though I realise the latter is probably too much to hope for...)
Thanks,
- David Prokopetz.

Rocks such are jade (nephrite, jadeite varieties), are considered hard stones
since their mineral constituents have high indentation hardnesses and must be
carved by continuous abrasion or lapping. Jadeite has a high specific gravity
(3.25 - 3.35), a hardness of 6.5-7.0 (nephrite) or 6.5-7.0 (Jadeite), is
generally fine-grained fibrous, also massive or granular, which in combination
with its chemical composition (Na(Al, Fe)Si2O6, Sodium Aluminum Iron Silicate),
and the interlocking nature of it's crystal growth likely gives Jadeite the
strength which it so famously exhibits. Although it has one good cleavage
(110), the fact that it is usually found in compact lenses, veins, or nodules
(the crystals being locked together, usually at 90 degrees) in outcrop makes
this 'flaw' practically negligible. Jadeite is formed in a high pressure
metamorphic environment. The addition of chromium give Jadeite it's
characteristic color.

Check out these sites:

http://encyclopedia.thefreedictionary.com/Nephrite%20jade

http://www.jewelrysupplier.com/2_jade/jade_properties.htm

http://mineral.galleries.com/minerals/silicate/jadeite/jadeite.htm

http://webmineral.com/data/Jadeite.shtml

http://www.jadesite.com/physical.html

http://www.ventanamining.com/products/dimension.htm#3

"Chad Walker, project manager at Sierra Testing Laboratories, reported that the
jadeite had a significantly higher compressive strength than any other rock
material that lab has ever tested. The jadeite dented the stainless steel
platens and almost exceeded the capacity of the hydraulic press used in the test
procedure. The average compressive strength of the 3 jadeite samples tested was
53,870 psi. This is twice the strength of the average granite and 2.5 times the
strength of the best-quality marble on the market today."

"The modulus of rupture test is performed on a brick-sized sample. The sample is
supported from below on either end while a load is applied to the sample in the
middle. The modulus of rupture of the jadeite was 7,450 psi. This is 3.5 times
stronger than the average quartzite and 7.5 times stronger than the average
marble."

"Jadeite is roughly 500 times more abrasion resistant than marble. Jadeite has a
scratch hardness of 6.5 to 7 on the Moh's scale, the same as quartz. It is more
resistant to scratching than any other dimension stone except the best quality,
well-cemented quartzite. Jadeite has exceptional toughness or resistance to
chipping and cracking, and is significantly tougher than any other dimension
stone, including quartzite. Jadeite is the toughest of all gem materials and is
tougher, but not harder than diamond. Diamond will scratch jadeite. Jadeite will
crush diamond."

[will e]

Hi David, I once found several small nodules of jade (nephrite) in northern
California and brought them home to cut. I tried to break one nodule open
with a hammer on the garage floor. Nothing happened to the jade, but left a
dent on the concrete floor. Sort of like trying to break a phone book with a
hammer. The interlocking fibers produce a very tough material. Will E.

Post by David Prokopetz
Hi.
I have a question about the properties of jade. While perusing a text on
Chinese history, I came upon a claim that jade is "stronger than steel", and
that its utility in manufacturing tools and weapons was limited only by the
rarity of large, unflawed pieces to work with. This struck me as an odd
assertion, and I decided to follow up on it; I found it to be repeated in
several books on mineralogy I have on hand, including one which more
specifically states that "fine-grained jadeite [...] has greater tensile
strength than steel".
However, I'm not able to find any actual data to back this up; all the
sources I've checked list jadeite's *hardness* (which does indeed compare
favorably to that of hardened steel, both ~7 on Moh's scale), but none have
numerical data on jadeite's toughness, tensile strength, or anything else
that would allow a more comprehensive comparison. Does anyone know of a
source that contains the information I'm looking for - or, better yet, an
actual comparative study?
(Though I realise the latter is probably too much to hope for...)
Thanks,
- David Prokopetz.

[Jaap Bos]

Hallo David,

I found a (rather incomplete) reference to an article on the comparative toughness of nephrite,
jadeite and other minerals.
Seems that it can be found in the july 1973 issue of the "American Mineralogist".
Hope this helps.

Groeten,

Jaap

Post by David Prokopetz
Hi.
I have a question about the properties of jade. While perusing a text on
Chinese history, I came upon a claim that jade is "stronger than steel",

and

Post by David Prokopetz
that its utility in manufacturing tools and weapons was limited only by

the

Post by David Prokopetz
rarity of large, unflawed pieces to work with. This struck me as an odd
assertion, and I decided to follow up on it; I found it to be repeated in
several books on mineralogy I have on hand, including one which more
specifically states that "fine-grained jadeite [...] has greater tensile
strength than steel".
However, I'm not able to find any actual data to back this up; all the
sources I've checked list jadeite's *hardness* (which does indeed compare
favorably to that of hardened steel, both ~7 on Moh's scale), but none

have

Post by David Prokopetz
numerical data on jadeite's toughness, tensile strength, or anything else
that would allow a more comprehensive comparison. Does anyone know of a
source that contains the information I'm looking for - or, better yet, an
actual comparative study?
(Though I realise the latter is probably too much to hope for...)
Thanks,
- David Prokopetz.

[d***@onlinehome.de]

David,

I would never fight with a sword of Jade against a sword of steel ! In
this case I should better throw Jade lumps on the enemy ...
I have some expiriences with Jade in the sight of cutting and
polishing - it' a terrible, heterogene material. Because of the
genesis Jade is a partly fibrous stone with a lot of micro fissures;
mostly you must suffer after giving the stone a form with grinding
material down to 400 mesh a nasty break. That's very hard, especially
in the case of best coloured Jade lumps.
OK, the best parts of a Jade lump are a bit harder than hardened
normal steel ... but fight with steel and take Jade only for jewels or
cult objects.

Wolfgang

Post by David Prokopetz
Hi.
I have a question about the properties of jade. While perusing a text on
Chinese history, I came upon a claim that jade is "stronger than steel", and
that its utility in manufacturing tools and weapons was limited only by the
rarity of large, unflawed pieces to work with. This struck me as an odd
assertion, and I decided to follow up on it; I found it to be repeated in
several books on mineralogy I have on hand, including one which more
specifically states that "fine-grained jadeite [...] has greater tensile
strength than steel".
However, I'm not able to find any actual data to back this up; all the
sources I've checked list jadeite's *hardness* (which does indeed compare
favorably to that of hardened steel, both ~7 on Moh's scale), but none have
numerical data on jadeite's toughness, tensile strength, or anything else
that would allow a more comprehensive comparison. Does anyone know of a
source that contains the information I'm looking for - or, better yet, an
actual comparative study?
(Though I realise the latter is probably too much to hope for...)
Thanks,
- David Prokopetz.

[David Prokopetz]

Post by will e
David,
I would never fight with a sword of Jade against a sword of steel ! In
this case I should better throw Jade lumps on the enemy ...
I have some expiriences with Jade in the sight of cutting and
polishing - it' a terrible, heterogene material. Because of the
genesis Jade is a partly fibrous stone with a lot of micro fissures

Well, yes, but that just gets back to the "unsuitable due to rarity of
unflawed pieces" issue, which the original article did mention. I'm more
interested in the properties of jadeite as a substance, not the difficulties
of working with jadeite as found in nature.

- David Prokopetz.

[d***@onlinehome.de]

Post by David Prokopetz

Post by will e
David,
I would never fight with a sword of Jade against a sword of steel ! In
this case I should better throw Jade lumps on the enemy ...
I have some expiriences with Jade in the sight of cutting and
polishing - it' a terrible, heterogene material. Because of the
genesis Jade is a partly fibrous stone with a lot of micro fissures

Well, yes, but that just gets back to the "unsuitable due to rarity of
unflawed pieces" issue, which the original article did mention. I'm more
interested in the properties of jadeite as a substance, not the difficulties
of working with jadeite as found in nature.
- David Prokopetz.

OK, here I have some datas from my german minerals book (but I'm a
little in doubt, wether the hardness datas are real correct for every
Jade; what a Jade type was taken, what was the amount of
fibrous/microcystalline material, was only taken the best type like
Will's concrete floor killer ???) :
Lehrbuch der Mineralogie
H.J. Rösler
5th edition from 1991 (Deutscher Verlag für Grundstoffindustrie,
Leipzig)
ISBN 3-342-00288-3
"Jadeit NaAl[Si2O5], 20% NaO, 25% Al2O3, 55% SiO2, diadochial content
of little amounts of Ca, Mg and Fe, monokline Alkalipyroxene.
Glassy gloss, Brix n=1,659
Hardness 6,5-7; unusual tough.
Splitability along (110) : 2 (on a scale from 0 "without" to 5
"complete")
Density 3,3-3,4 g/cm3
Not decomposible in acids."
Unfortunately is no hint given, from what the green colour is coming.
In several alkalisilicates is only Fe needed for a rather nice green -
additional Cr may give a better green.

Wolfgang