The Naked Scientists

The Naked Scientists Forum

Author Topic: Gemstones !!..are nice !..but whar are they all about ?  (Read 15826 times)

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Dearest Sirs/Madams/Heshe's/Shehe's/Trangsgenders/Transexuals/confused !

These are nice aren't they ?



and they're mine mine mine mien....not yours ..but mine...so there  *sticks tongue out and blows raspberry*

But what are Gemstones ?...why are they so different from each other ?...me likes the colours...but why are there so many shades and hues and tones of Gemstone luff and joy ?

me don' know....do you ?



 

Offline eric l

  • Hero Member
  • *****
  • Posts: 514
    • View Profile
Gemstones !!..are nice !..but whar are they all about ?
« Reply #1 on: 01/05/2007 17:14:20 »
It is a very long story (millions of years to be exact) but I'll try to cut it short.

It starts with a volcanic eruption (or sometimes within the magma without an eruption).  The molten lava solidifies, and the volatiles leave bubbles, which are not filled up as the viscosity of the lava increases dramatically on cooling.  So here we are with something like cheese with holes in it (also created by volatiles, in this case by products of the fermentation process).

Next, it starts to rain.  The water dissolves all kinds of minerals, like SiO2 or Al2O3, and this water accumulates in the holes.  The minerals start to crystallize and form nodules, also known as "geodes".  In the case of SiO2 you will obtain agate, with Al2O3 you obtain corundum.

Now of course, the water has dissolved other things besides 2 or Al2O3, and this "impurities" are responsible for the colours.  Because the concentration of this "impurities" is not constant, you can obtain striped varieties, and so on.

Wether it will be a gem will depend on the colour, sometimes on the stripe pattern, and on transparency.  If your stone is opaque rather than transparent, it may be just as useful for technical applications as the gem.  The "rubies" is a watch for example are are often opaque corundum rather than the transparent red variety.

To be complete :  diamonds are not formed by carbon dissolved in water crystallizing in the bubbles, bu by the pressure on the carbon particles as the volcanic rock solidifies and shrinks.  And occasionally, some minerals that are neither the agate nor corundum type qualify as gemstones (e.g. malachite, which is actually a copper mineral or lapis lazuli, which is actually a mixture of different minerals).

 
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Gemstones !!..are nice !..but whar are they all about ?
« Reply #2 on: 01/05/2007 18:00:30 »
It is a very long story (millions of years to be exact) but I'll try to cut it short. That's OK.. I got time !!

It starts with a volcanic eruption (or sometimes within the magma without an eruption) ooooh !!..wooosh wooosh !!..YAYYYYYYY !!!.  The molten lava solidifies,Just like wifyes sponge cake !! and the volatiles leave bubbles, which are not filled up as the viscosity of the lava increases dramatically on cooling.  So here we are with something like cheese with holes in it (also created by volatiles, in this case by products of the fermentation process). This is wonderful thank you Eric

Next, it starts to rain. Me luffs the rain...it's well....rainy ! The water dissolves all kinds of minerals, like SiO2 or Al2O3, and this water accumulates in the holes.  The minerals start to crystallize and form nodules, also known as "geodes".  In the case of SiO2 you will obtain agate, with Al2O3 you obtain corundum. I think we have what must be Geodes too...my son has a whole big bunch of them

Now of course, the water has dissolved other things besides 2 or Al2O3, and this "impurities" are responsible for the colours. THANKYOU
  Because the concentration of this "impurities" is not constant, you can obtain striped varieties, and so on.Aha !!..this explains it...Marvellous

Wether it will be a gem will depend on the colour, sometimes on the stripe pattern, and on transparency.  If your stone is opaque rather than transparent, it may be just as useful for technical applications as the gem.  The "rubies" is a watch for example are are often opaque corundum rather than the transparent red variety.

To be complete :  diamonds are not formed by carbon dissolved in water crystallizing in the bubbles, bu by the pressure on the carbon particles as the volcanic rock solidifies and shrinks.  And occasionally, some minerals that are neither the agate nor corundum type qualify as gemstones (e.g. malachite, which is actually a copper mineral or lapis lazuli, which is actually a mixture of different minerals). THANKYOU ..Yes..I was upset to not see a diamond amongst my collection !!..I wonder why that is !! ? ;) ;)

 
THANKYOU very much indeed Eric !!...I really appreciate the time it took you to respond...Hugs the Eric
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Gemstones !!..are nice !..but whar are they all about ?
« Reply #3 on: 01/05/2007 19:58:25 »
Good work Eric. I do have a couple of clarifications. For example Sodalite is a feldspathoid or a mineral resembling feldspar and occurring in rare igneous rocks.  Amethyst is a purple quartz most often found in Pegmatite dikes, as is the rose quartz,  Amazonite is a green microcline feldspar found in granites; Aventurine can be the name given to either a type of feldspar or a type of quartz.   

An interesting thing about all of the tiger eye gemstones is that they are all quartz replacement of different types of amphiboles, which are fibrous silicates.
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Gemstones !!..are nice !..but whar are they all about ?
« Reply #4 on: 01/05/2007 20:23:53 »
Good work Eric. I do have a couple of clarifications. For example Sodalite is a feldspathoid or a mineral resembling feldspar and occurring in rare igneous rocks.  Amethyst is a purple quartz most often found in Pegmatite dikes, as is the rose quartz,  Amazonite is a green microcline feldspar found in granites; Aventurine can be the name given to either a type of feldspar or a type of quartz.   

An interesting thing about all of the tiger eye gemstones is that they are all quartz replacement of different types of amphiboles, which are fibrous silicates.

well...of course  I knew all that !!...sheesh !!!...just as I'm about to respond,.........Jimmyboy goes and posts a post virtually word for word what I was going to say !!...

Hugs the Jim Bob and THANK YOU also for your clarification !
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Gemstones !!..are nice !..but whar are they all about ?
« Reply #5 on: 01/05/2007 21:40:17 »
Thank you Sir Neil, you are so kind, so good so articulate - slober, slober ....


Next, it starts to rain.  The water dissolves all kinds of minerals, like SiO2 or Al2O3, and this water accumulates in the holes.  The minerals start to crystallize and form nodules, also known as "geodes".  In the case of SiO2 you will obtain agate, with Al2O3 you obtain corundum.
 

I must make a correction. Corundum is never found as a replacement mineral. It is always found in igneous rocks, the gems, sapphires and rubies, are found in lampropyrie and pegmatite dikes. Sorry I didn't catch that earlier.
« Last Edit: 01/05/2007 21:42:03 by JimBob »
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Gemstones !!..are nice !..but whar are they all about ?
« Reply #6 on: 01/05/2007 21:49:34 »
Jimmy Boy....me is well happy that ewe is impressed by my articulate niceness !!

LOL..may I ask ?....does this mean that there could be any number of other gemstones still to be discovered considering the nature of their creation ?
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Gemstones !!..are nice !..but whar are they all about ?
« Reply #7 on: 02/05/2007 21:40:12 »
Perhaps but not very likely.

The stone age peoples had to be VERY observant of their environment as their lives depended on it. I doubt they missed much as all of these stones have been valued for well over 2000 years
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Gemstones !!..are nice !..but whar are they all about ?
« Reply #8 on: 02/05/2007 22:32:20 »
Perhaps but not very likely.

The stone age peoples had to be VERY observant of their environment as their lives depended on it. I doubt they missed much as all of these stones have been valued for well over 2000 years

Well, I suppose you would know...after all...you were there !!..LOL  ;D ;D


*shoots himself in the foot*
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Gemstones !!..are nice !..but whar are they all about ?
« Reply #9 on: 03/05/2007 00:32:41 »
Neil,

Please, you know how sensitive I am about my age!

(where are my teeth, I can't gum this gruel ...)
 

The Naked Scientists Forum

Gemstones !!..are nice !..but whar are they all about ?
« Reply #9 on: 03/05/2007 00:32:41 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums