Not even close to "pure". I purchased this product for analytical electroplating, and dissolved 240g in 1L of distilled water. After noticing the solution had a few odd properties, we decided to do some analyses. Here's why it's not Zinc Sulfate: 1. Zinc Sulfate forms a clear solution, this forms a yellow/brown solution. 3. The true saturation point of Zinc sulfate is 570g/L, and this powder had a saturation point of well below 240g/L. 2. At saturation, ZnSO4 (Zinc Sulfate) will be a weakly basic solution. After dissolving it, ours was acidic with a pH of 4.74. 4. Strong bases (NaOH) should not react with the solution, but in our case they reacted and formed a dark green precipitate.

Not zinc sulfate. At least not all zinc sulfate, maybe there's some zinc sulfate in there, hard to tell. Zinc Sulfate, according to the literature is soluble in water at 57.7g per 100 mL of water. Pretty freely soluble. This material does not fully dissolve at substantially lower concentrations. Watching closely is does appear that it is a mixture of at least two components. When you add it to water it clumps together at the bottom. A gentle swirling does show diffraction line, a clear indication that something is going into solution. However there is also a flocculent white material that is completely insoluble, even upon boiling. It looks a little like silica gel to me but it's hard to tell without sending it out to a lab.

I bought this for my pecan tree. My pecan tree only produces a significant crop every other year. In 2015, I got almost 100 pounds of pecans. So I would have expected nothing in 2016. I applied this + 8 lbs of 10-10-10 (4 lbs per diameter of tree trunk measured 4 feet from ground -- diameter is circumference divided by Pi (3.14)). So in 2016 instead of getting no nuts, I got almost 70 lbs. And this was during a drought! How much was the 10-10-10 versus the zinc? I have no idea. But I'm not giving the treatment in 2017 -- freezer is full of pecans!

Did a good job on my mother's goats and sheep who had hoof rot.

No directions for application are included. Use two teaspoons powder per one gallon of water. Apply to tree trunk and branches when tree is dormant. Do not spray on green leaves, unless the tree is about to go dormant. I mixed 10 gallons and sprayed to the ground at the drip line of the tree because my tree was already going green.

Should have done this long ago. My trees look like they have gotten a shot of steroids