40x – A 99.9+% pure fragment of antimony in 1 drop of water on glass slide. The laminar (platelets) structure are visible. This piece of antimony was broken off a fist size hunk that melted by an induction furnace.

40x – The same piece of Sb pictured above, but now with surface is becoming pacified with what I suspect antimony oxide in this solution of 1 drop HNO3 & 2 drops H2O
This surface pacification can be accelerated by dissolving only in HNO3.

40x – The entire surface of the antimony is thoroughly pacified, which won’t allow further nitric acid attack.
The pinkish tint is reflected light from my hand on focusing knob.
This white crystalline structure and behavior seems to be a very good way of indicating the presence of Sb in this type of solution.

10x – At about 11 o’clock is the large Sb crystal that is coated white with what I presume to be an oxide.
Clearly, this type of surface pacification is a fundamental clue regarding the presence of Antimony, whether only tiny bits on a rock fragment or say on a piece of galena. Whereas Galena also under same type of solution circumstance also makes a white surface pacification the Lead nitrate crystals look much different.

40x – At about 11 o’clock is an inserted K2Cr2O7 crystal in the 1 drop HNO3 + 2 drops H2O.
The white fragments are the Sb (oxides?).
As the potassium dichromate dissolves it slightly colors the white flocculent.

10x – The potassium dichromate (K2Cr2O7) only produced this reddish and yellowish solution color and failed create any precipitation.

In a separate solution of 1 drop HNO3 & 2 drops H2O with NaCl (table salt with no trace Iodine) inserted failed to produced any precipitation. Several more sodium chlorides crystals were added and no precipitant formed.

The concluding viewpoint is that K2Cr2O7 and NaCl are not appropriate reagents in determining the presence of Sb in nitric acid solutions.

Metallic Antimony does not dissolve in HCl.

10x – A crystal of KI introduced to the 1 drop HNO3 + 2 drops water that has been further diluted with 2 additional drops of H2O.There is a decided reaction taking place, which is further illustrated in the next 4 images.

10x – This KI reaction changes shape and color, which suggests reaction with NOx.

30x – A magnified view of the preceding image that is fast changing shape and color.
There is a little evidence of Iodine reduction (blackish) occurring in the 8 o’clock area and within the void area that has a reddish color..

40x – Further magnification shows not only the now red color, which may be antimony iodide, but may also be a reaction color with the nitric acid or some other form of NOx.
What was black has now become more brown, but nonetheless a reaction took place and not a complete precipitation.

40x – The red coloration is practically all gone and leaving behind this black and brownish ill-definable crystallization, which partly I suspect is reduced Iodine. However, there is some definite red coloration that I could not determine if crystal or simply colored solution.

10x – Conducted another new microchem, which began with 3 drops water and 1 drop HNO3 with a little heat to help digest the Sb particles. Then 2 more drops of water was added and a single crystal of KI (yellow area). The KI dissolved almost instantly, and formed the next precipitation before I could finish capturing, naming and saving this image.

10x – I would say that this was a decent precipitation until what began to happen in the next image.

25x – The yellow-orange crystals, which were formally white are now reacting and becoming a reddish-brown.

35x – A magnified view of the preceding image where each orange colored particle is self destructing. The area at 6 to 9 o’clock is rapidly expanding inwardly and color changes are easily noticeable. I would hazard a guess that this is Iodine trying to reduce.

25x – Before the yellow orange area at right changed colors (orange to brown) another KI crystal was inserted in the upper left corner, causing a fast spreading yellow precipitation.
I suspect that the 1st precipitation at right reduced the amount nitric acid, which allowed the 2nd fast expanding yellow precipitation.

27x – Because the previous KI tests were clearly inconclusive another microchem was conducted that was more diluted. The process was: 1drop HNO3 + 3 drops H2O + heat, added 1 more drop + more heat, then added 2 drops water and more heat to digest the Sb fragments on the glass slide. Not all the metal fragments are dissolved as indicated bu the round, blank looking areas which are actually metal not in focus.
Focus is on the white gelatinous looking formations that resemble silica, which is actually a form of Sb.
Each drop of water caused very fine particles of this fluffy white to fall out of solution. Normally, I would suspect this white stuff to be a hydrate of Sb, but according to the books there is no such thing.
Regardless of what the actual chemical structure of this white flocculent this is another big clue in helping to determine the presence of Sb in a nitric acid solution.

10x – A low magnification of the preceding image.

10x – A single crystal of KI inserted in above left top corner of solution, which quickly dissolved.

10x – Only a couple seconds lapsed and this colored portion of the expanding precipitation appeared.
Is this still a reaction where Iodine is trying to be reduced?

10x – The precipitation has expanded further in the solution and changed to a little darker color.

40x – Although the yellow-orange precipitation is still expanding it does not seem to actually change the color of the white, except as a coating.
When heat is applied the Iodine reaction to diluted HNO3 occurs rapidly, as these white gelatinous formations seem to be harboring HNO3.
I cannot, as yet with only a few tests make any positive conclusions regarding the efficacy of KI in determining Sb.

10x – This toothpick tip was dipped into the original solution, then ignited to see if any metal would reduce.

10x – Even though no metal reduced I did not expect much, if any, because antimony is so easily volatilizes.
The white area was re-exposed to the cigarette lighter flame and neither the reducing nor oxidizing parts of the flame produced visible metal that could be seen at 70x.

More microchems on antimony will be posted as time allows.