Difference between revisions of "Heavy Liquids"

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(Methylene Iodide)
(Methylene Iodide diluted with Toluol)
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====Methylene Iodide diluted with Toluol====
 
====Methylene Iodide diluted with Toluol====
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This liquid can easily seperate Tourmaline (3.05) from Topaz (3.5) as the first will suspent while Topaz will sink in this liquid.
  
 
====Bromoform====
 
====Bromoform====

Revision as of 09:19, 5 October 2006

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This section is currently under construction, do not edit until this message is gone
--Doos 05:23, 5 October 2006 (PDT)


Heavy liquids are substances in liquid form that have a known specific gravity (SG) and are used as a means of quick seperation of stones with similar appearance. In general these liquids are highly toxic and precautions should be taken when used.

Basic

Heavy liquids are stored in dark, transparent bottles to prevent light from influencing their physical properties and should be stored closed with a stopper to prevent evaporation.

Safety warning

Before using heavy liquids it must be stressed that one should avoid all contact with the skin and that they are non-potable. Always use tweezers to insert the gemstones and when in contact with the skin, you should thouroughly wash. When in contact with eyes, you should rinse your eye with streaming water and contact your medical Dr. immediatly.

Always use heavy liquids in a well ventilated environment and they should be kept away from children and pets.

Use of heavy liquids

The use of heavy liquids is fairly straightforward. When a stone is immersed into the liquid it will either float, suspent or sink.

When the SG of the liquid is known, take the gemstone in your tweezers and gently lower the stone in the liquid. Observe the stone while looking through the side of the bottle and take the stone out again with your tweezers.
Carefully rinse the stone and tweezers under streaming water (you might want to take precautions to not let the stone go down the sewers). Or you could rinse it in a large beaker filled with clean water.

After your observations you should be able to tell if the stone is of higher, lower or equal SG than the liquid used.

  • When the stone floats in the liquid, it will have a lesser SG than the liquid.
  • When the stone is suspending in the liquid, it will be of equal SG as the liquid.
  • When the stone sinks, it will have a higher SG than the liquid.

One can also observe to which degree a stone will sink or float after suspending it in the liquid.
For instance when the stone sinks rapidly, it will have a far greater SG than the liquid.

Types of heavy liquids

In gemology generaly 4 heavy liquids are used.

  • Methylene Iodide - SG = 3.33
  • Methylene Iodide diluted with Toluol - SG = 3.05
  • Bromoform - SG = 2.85
  • Bromoform diluted with Toluol - SG = 2.65

In addidion Clerici Solution with a SG of 4.2 is used in laboratories which can be diluted with water to bring it down to SG = 4 or SG = 3.52 for instance. This solution is extremely toxic and should only be used in a well equipped laboratory with additional safety precautions as an acid chamber.
Dr. W. Wm. Hanneman suggested the use of Sodium Polytungstate as a non-toxic alternative for most heavy liquids.

Methylene Iodide

Methylene Iodide (CH2I2) is also named di-idiomethane and has a SG of about 3.33.

Yellow Topaz (3.5) will sink in this liquid whilst Citrine (2.65) will float.

Methylene Iodide diluted with Toluol

This liquid can easily seperate Tourmaline (3.05) from Topaz (3.5) as the first will suspent while Topaz will sink in this liquid.

Bromoform

Bromoform diluted with Toluol

Clerici Solution

Sodium Polytungstate