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12AX7
Post Harlot
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I get that all the time with salt solutions. Raft forms on the surface, crusts crawl up the sides and in towards the center, it's like a pond
freezing over. It always annoys me because it really obscures the surface that I need for evaporation.
Tim
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undead_alchemist
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Got the following crystals overnight.
This is in the bottom of a 1L beaker.
Will post more when I get them out of the beaker.
Edit by Chemoleo:
Beautiful crystals but please state what the substance is!
[Edited on 14-7-2008 by chemoleo]
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indigofuzzy
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| Quote: |
Vera nice. What were your starting materials? What color are they? I.e., more blue than green, more green than blue, or blue-green, etc. (I'm
thinking the camera may distort this color somewhat.)
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Thanks 
I used Copper Carbonate and distilled white vinegar.
The copper carbonate was made from copper sulfate and sodium bicarbonate.
The copper sulfate was made by electrolysis of Magnesium Sulfate with a copper anode.
(Yup, from copper metal to copper acetate in 3 painstaking slow steps  )
The crystals seem more green to me, but I've noticed that people draw the line between blue and green at different colors. But it's certainly bluer
than a 532nm laser.
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jgourlay
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| Quote: | Originally posted by indigofuzzy
| Quote: |
Vera nice. What were your starting materials? What color are they? I.e., more blue than green, more green than blue, or blue-green, etc. (I'm
thinking the camera may distort this color somewhat.)
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Thanks
I used Copper Carbonate and distilled white vinegar.
The copper carbonate was made from copper sulfate and sodium bicarbonate.
The copper sulfate was made by electrolysis of Magnesium Sulfate with a copper anode.
(Yup, from copper metal to copper acetate in 3 painstaking slow steps )
The crystals seem more green to me, but I've noticed that people draw the line between blue and green at different colors. But it's certainly bluer
than a 532nm laser. |
Does that mean that you also got magnesium plated out?
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indigofuzzy
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Actually, I got a pesky crust of Magnesium hydroxide all over the cathode at first. After a while, when the concentration of magnesium in soln had
dropped, small amounts of copper hydroxide began to form in the cathode cell.
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chemoleo
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A beautiful crystal aglomerate:
Now this is something I'd like to be able to grow (anyone, how?):
Stibnite
Stibnite, sometimes called antimonite, is a sulfide mineral with the formula Sb2S3
http://en.wikipedia.org/wiki/Stibnite
Photo taken at the Museum of Natural History, London
Size: 30 cm wide, 25 high and 25 deep.
[Edited on 14-10-2008 by chemoleo]
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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chemoleo
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Crystal Healing
And this is how they help you to battle disease, of mind and body:
| Quote: | Chemical Composition
The vibrational frequency of the elements that make up crystals is also used in crystal healing.
To understand the importance of the chemical make-up of minerals, let's look at a few examples:
* Calcite ( CaCO2), you will find by looking at the periodic table, is a calcium carbonate. Most
people will know that calcium is the main constituent of the skeletal system, and therefore calcite is often used in crystal healing to help mend
fractures of bones.
* Hematite (Fe2O3) is an iron oxide. Iron helps to maintain healthy red corpuscles and oxygenate the blood, and hematite is frequently used to
treat anaemia as well as circulatory problems.
* Malachite (Cu2(CO3)(OH)2) contains mainly copper, which draws off heat, and can therefore be used to reduce inflammation. This is the idea
behind the use of copper wrist bands to treat osteoarthritis.
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Makes sense to me
Nonetheless a good source for interesting minerals.
http://www.crystalage.com/ (where the excerpt from above is from).
[Edited on 13-10-2008 by chemoleo]
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Panache
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| Quote: | Originally posted by chemoleo
And this is how they help you to battle disease, of mind and body:
| Quote: | Chemical Composition
The vibrational frequency of the elements that make up crystals is also used in crystal healing.
To understand the importance of the chemical make-up of minerals, let's look at a few examples:
* Calcite ( CaCO2), you will find by looking at the periodic table, is a calcium carbonate. Most
people will know that calcium is the main constituent of the skeletal system, and therefore calcite is often used in crystal healing to help mend
fractures of bones.
* Hematite (Fe2O3) is an iron oxide. Iron helps to maintain healthy red corpuscles and oxygenate the blood, and hematite is frequently used to
treat anaemia as well as circulatory problems.
* Malachite (Cu2(CO3)(OH)2) contains mainly copper, which draws off heat, and can therefore be used to reduce inflammation. This is the idea
behind the use of copper wrist bands to treat osteoarthritis.
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Makes sense to me
[Edited on 13-10-2008 by chemoleo] |
That explains how plaster casts work their magic, ohhhh!! Its becasue they have calcium in them. But wait last broken arm i had was mended using an
epoxy cast, how could that possibly work????
I'm confused i might call my raiki teacher.
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not_important
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| Quote: | Originally posted by chemoleo
Now this is something I'd like to be able to grow (anyone, how?):
Stibnite
Stibnite, sometimes called antimonite, is a sulfide mineral with the formula Sb2S3 |
SFAIK it is formed hydrothermally, at temperatures in the range of 100 to 300 C with the lower end forming small grains. The fluid is halide solutions
approximating sea water but over a wider range of concentrations, and possibly containing additional sulfides.
So, a pressure system at 150 to 200 C, with a temperature gradient, the hot side having a supply of powdered Sb2S3 and maybe a little free sulfur, the
aqueous fill being NaCl at about sea water concentration with Na2S at about 5% of the amount of NaCl. Seal it up, turn on the heat, and go away for a
long time.
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watson.fawkes
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| Quote: | Originally posted by not_important
SFAIK it is formed hydrothermally, at temperatures in the range of 100 to 300 C with the lower end forming small grains. The fluid is halide solutions
approximating sea water but over a wider range of concentrations, and possibly containing additional sulfides. |
Stipulating that these are the geologic conditions of formation (which may have included reactions), are there other conditions more
amenable to low-end laboratory work? Is there some other solvent to use with a more friendly temperature-pressure behavior?
Stibnite is one of my favorite minerals. It's Arabic name is "kohl" and it's the origin of the loan-word "alcohol". The reasons for this involve the
early Arab chemical theories of Jabir, a topic for another thread. It was anciently used, and is still, as eye makeup. These large crystals are
impressive and, I imagine, rare.
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chemoleo
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Yes, I'm sure this is about the best you can get, in the same section of the museum they displayed one of the largest natural gold pieces in the
world, meteorites, lunar rock etc.
The conditions remind me of those with quartz, where superheated water (300 deg C) dissolves SiO2, which then deposit over the eons as the beautiful
crystals we know. Quartz can be grown commercially over a matter of years (!), too.
Regardless - Not_important, could you please quote the reference for this? Particularly if it is out of a book? Thanks.
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Nick F
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I've been growing some quite nice thorium nitrate crystals recently, I'll get a photo when my camera batteries have charged up. I put a solution into
a little vial, and placed this into a jam jar with some silica gel at the bottom. Some of them are approaching 1cm across now. I might try to get out
one of the larger ones, then add more water to dissolve the rest, then replace the crystal as a seed.
I'll try it with uranyl nitrate too, that should make some nice looking crystals!
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Magpie
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My supplies of ferrous salts were covered with ferric salts so I decided to recrystalize them to try to get better quality.
For the ferrous ammonium sulfate hexahydrate I dissolved up the crappy crystals I had made previously, added a bright nail and kept the soln near
boiling for a few minutes. The solution cleared to a yellow-green translucence. Then I filtered hot into a crystalizing dish. In three days large
pale-green crystals had formed (see below on right). These were air dried. As you can see some ferric salt has formed on the edges of the cystals.
For the ferrous sulfate heptahydrate I started with crappy pottery grade material. I dissolved some in water, added a bright nail and a couple ml of
H2SO4, heated and filtered. When the crystals were about 5mm I washed them twice w/water, then twice with alcohol (S-L-X). These were air dried.
The crystals in the 2 leftmost bottles appear to be somewhat efflouresced. The right bottle crystals were harvested when about 2mm in diameter and
dried at room temperature, but not over dried. They appear to be of the best quality.
Whereas the ferrous ammonium sulfate is known for its supposed resistance to oxidation, my experience has been that the ferrous sulfate is more
reisistant. However, with the FAS I did not wash the crystals with water and alcohol.
What has beenyour experience making these salts?
Reference: "A Course in Inorganic Preparations," by Henderson & Fernelius
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chemoleo
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Same here - I was hugely disappointed with ferrous ammonium sulfate - not only is the colour ugly, but also it's prone to oxidation. But I didn't have
much good experience with FeSO4 hydrate either... the iron curse!
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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chief
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Stibnite is no problem: Use gas-phase transport (CVT) :
==> put somewhat raw-material into an ampoule, + an calculated excess of Sulfur (so that the pressure doesn't get too high)
==> evacuate well
Now heat the both ends of the ampoule to different temperatures, maybe 500 vs. 700 [Celsius], for several days (good double temp-regulation required)
; the S2-vapor reacts with the Stibnite, transports it to the cooler end of the ampoule (therefore at the beginning all raw-material should be at the
hot end), and crystals grow. Once the parameters are experimented out, any much larger vessel may be used, with kg's of material ...
Thats also one way to grow good ruby-crystals, only at much higher temperatures (1400 [Cels]), and not with sulfur ... ; there are other ways however
...
[Edited on 7-3-2009 by chief]
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Magpie
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| Quote: |
But I didn't have much good experience with FeSO4 hydrate either... the iron curse!
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Chemoleo, I didn't have much luck on my first try with FeSO4*7H2O either. All I got was a bunch of rust. So, thinking it wasn't concentrated enough
and acid enough I added more crude FeSO4, another bright nail, some H2SO4, and heated it back up for a few minutes. Then I filtered it again into a
crystallizing dish. From then on I got four crops of crystals without a trace of rust. I think the liquor must be definitely acid, like pH 1-2.
It was interesting to me that when cleaning glassware, as the saturated liquor was diluted with water, it would instantly turn to rust!
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DJF90
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Magpie: We made ferrous ammonium sulfate (Mohr's salt) at school and we ended up with much brighter crystals (yet still pale green) than your picture
shows. The teacher had a sample in an uncovered pertri dish that was about 5 years old, on the windowledge. It was identical to the crystals we had
made that day, albeit a little dusty lol!
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Magpie
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| Quote: |
Magpie: We made ferrous ammonium sulfate (Mohr's salt) at school and we ended up with much brighter crystals (yet still pale green) than your picture
shows.
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Well come on DJF90, tell us how you did it! 
[Edited on 7-3-2009 by Magpie]
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DJF90
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The textbook with the method in is at home. I'm at college now but we finish term next week so I'll make sure I post it up.
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DJF90
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Here is the preparation of Mohr's salt (ammonium iron (II) sulfate, (NH3)2SO4.FeSO4.6H20)
Making the Iron (II) sulfate
Heat 25ml of 2M sulfuric acid to boiling in a conical flask at least 250ml in size, remove the source of heat and add 2.8g of iron filings in small
portions. The energy given out by the reaction will keep the solution close to boiling. Keep a plug of cotton wool in the mouth of the conical flask
as much as possible to reduce the escape of acid spray.
When all of the iron filings have been added leave the mixture to continue reacting slowly. When the reaction slows down add an extra 10% of acid
(2.5ml). Meanwhile prepare the ammonium sulfate.
Making the Ammonium sulfate
Add 25ml of 2M sulfuric acid into a beaker and add sufficient 2M ammonia solution to neutralise the acid (ca. 50ml). Add the final portions in 5ml
amounts, until a drop of the mixture turns red litmus paper to blue. Boil the solution briskly to drive off the excess ammonia, and concentrate the
solution by leaving it boiling.
Separate the Iron (II) sulfate from the undissolved impurities and excess iron by filtering; collect the filtrate in a beaker containing 5ml of 2M
sulfuric acid to keep the solution acidic. Wash the filter paper with a small amount of water in order to collect all of the Iron (II) sulfate.
Making the double salt
Now add the Iron (II) sulfate solution to the ammonium sulfate solution. If the ammonia was not neutralised properly in the previous step the solution
will go cloudy and a little more acid should be added. Boil until the volume is reduced to about 40ml, then remove the source of heat and wait until
the beaker is cool enough to handle. Pour the concentrated solution of Mohr's salt into a dust-free, flat-bottomed crystallising dish, and cover with
a watch glass. Crystals may appear within an hour, but will probably take several days to form properly.
Procedure taken from "Nuffield Advanced Chemistry, 4th edition"
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Magpie
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Thank you DJF90 for posting these procedures. I note that keeping a small surplus of H2SO4 is mentioned for making the FeSO4 and the Mohr's salt.
This is consistent with my success in making FeSO4.
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DJF90
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I think that keeping the Fe(II) in an acidic environment is important to prevent its oxidation, and i believe this is achieved mainly by the presence
of NH4(+) in the Mohr's salt, and also by the small amount of excess acid.
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chemoleo
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This is interesting and may be the clue to this: When I tried to make the double salt I just used the respective analytical reagents in the correct
molar ratios (1:1). And I wasn't impressed with the result. Something to try again!
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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chemoleo
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Check this out:
http://news.bbc.co.uk/1/hi/sci/tech/8466493.stm
On the massive crystals at Naica cave! (see also a few pages ago where I posted pictures).
They should really do the video in 3 D!
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Paddywhacker
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There are many chemicals that are only very slightly soluble in water that might grow crystals vie the hydrothermal method. I have been thinking that
Thiel tubes might be useful in this context.
Has anybody experimented with ambient-temperature hydrothermal methods? What apparatus was used?
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