How could blue soil exist, in a realistic earth-like world. The world may even be earth.
First off is it even possible - could soil like this exist given the requirements below? (if not then why?)
Mainly what would the composition of the soil be (what elements/chemicals would be present that give the soil its color)?
What shade of blue? (representation could be given in hexcode (#0000FF) or an image maybe)
Would the soil be fertile or toxic or...?
The soil is just like normal earth soil. All the standard obvious earth soil stuff applies, difference is this soil is blue.
Plants must be able grow in it. Even if just sparsely weeds.
The soil may contain toxins, possibly even be radioactive.
No specific blue, but should be obviously blue, as in not blue-ish-some-other-color, but rather blue. Light blue, dark blue, etc. Blue in the sense that a person who was used to normal soil would clearly describe it as blue.
Solid blue, just as earth soil is solid brown. In other words not brown with little blue rocks or something.
The soil is permanently blue, not temporary.
The soil is not stained or tinted blue, but it's the composition or chemicals/elements in the soil that make it blue. (To me stained or tinted would be something like having the color altered by spilling paint, oil, etc on, etc. or tinted by light or light shining through something like colored glass.)
May be caused by a freak event. (if so what?)
Kind of what I was looking for here (as I thought that blue soil was not actually a thing at all) was actually something that would be more exotic, rare, but realistic, like for example the soil was compromised mostly of two elements that normally aren't found together and it is that combination that causes the blue.