Dukasaur wrote:HitRed wrote:wonder if the green is from copper
mookiemcgee wrote:I think most of the color is from sulphur
The yellow is almost certainly from sulphur. But I'm guessing the green is from iron sulphate.
It's true that copper sulphate is green in its solid form, but it turns blue when it dissolves, whereas iron sulphate stays green even in solution.
One complicating factor is that both iron and copper have 2 oxidation states or charges; iron can be +2 (ferrous) or +3 (ferric); copper can be +1 (cuprous) and +2 (cupric).
In my experience, actually holding and working with copper(II) sulfate, it is blue in the hydrated form and white if dehydrated. I got confirmation:
Copper(I) sulfate, also known as cuprous sulfate, is an inorganic compound with the chemical formula Cu2SO4. It is a white solid, in contrast to copper(II) sulfate, which is blue in hydrous form.
I not recalling having worked with copper(I) sulfate.
And Duk is right about sulfur, YELLOW. I do not recall working with iron(II) sulfate, but it is indeed green:
Iron(II) sulfate, also known as ferrous sulfate or copperas, is a chemical compound. Its chemical formula is FeSO4. It is made of iron and sulfate ions. The iron is in its +2 oxidation state.
Properties
It is a blue-green crystalline solid when hydrated and white when anhydrous.
both above from Wikipedia
and what about the other form of iron sulfate, iron(III) sulfate?
Iron (III) Sulfate formula or the ferric sulfate is an inorganic salt with the formula Fe2(SO4)3. It is yellow in colour and is soluble in water.
and
Iron (III) Sulfate Properties
Properties of Iron (III) Sulfate
Name Iron (III) Sulfate
Also Known as Ferric Sulfate, Sulfuric acid – iron(3+) salt
Appearance Yellow crystalline solid or greyish-white powder.
https://byjus.com/iron-iii-sulfate-formula/#:~:text=Iron%20(III)%20Sulfate%20formula%20or,and%20is%20soluble%20in%20water.Further, copper(II) ions make the aqueous (water) solutions blue [starting from copper(II) sulfate].
Copper metal (neutral or oxidation state zero) will, after "aging" and undergoing oxidation, stain concrete a bluish-green color. I am thinking of copper used as gutters on roofs, or the Statue of Liberty, too.
Why does copper turn green?
Have you ever wondered why copper does copper turn green? When left outdoors to the elements, copper transforms from a bright, shiny new penny shade, to a burnished brown, and finally to a distinct green color and makes it such a great choices for products such as copper awnings.
This unique characteristic of copper is completely natural and is often
referhttps://www.crescentcitycopper.com/index.htmred to as the “patina” – which referrers to the way copper changes color and turns green as it ages. This natural process actually preserves the copper and protects it from the outside elements.
Over time copper will naturally change colors – transforming from a shiny brown color to darker browns, then blues and finally greens after a number of years. When exposed to the natural elements such as wind and rain, copper develops this “patina” which actually protects and preserves the metal underneath.
Natural Oxidation
Just like rust develops on iron, patina develops on copper when the copper sulphate on the surface interacts with oxygen in the environment. Importantly, unlike rust which corrodes iron, patina actually protects and preserves the copper underneath.
https://crescentcitycopper.com/why-does-copper-turn-green/#:~:text=Over%20time%20copper%20will%20naturally,and%20preserves%20the%20metal%20underneath.and
When it was unveiled in 1886, it was a shiny brown color, like a penny. By 1906, the color had changed to green. The reason the Statue of Liberty changed colors is that the outer surface is covered with hundreds of thin copper sheets. Copper reacts with the air to form a patina or verdigris.
https://www.thoughtco.com/why-statue-of-liberty-is-green-4114936#:~:text=When%20it%20was%20unveiled%20in,form%20a%20patina%20or%20verdigris.And iron ions will cause the aqueous solution to have an orange color or tint.
These Color questions remind me of an experiment done in my first year in college to identify various ions in Lab. It took me several tests to identify about 7 ions in a selective and sequential set of steps. I had to go back to the Lab to confirm my various hypotheses. This experiment made me want to major in Chemistry, which is my undergraduate degree.
ConfederateSS.out!(The Blue and Silver Rebellion!)... 
