A relatively rare color of sands in collections is green and this is due to the fact that not so many minerals or combination of minerals can produce it. One of them is called glauconite, an iron silicate from the larger mica group, whose name derives from the Greek glaucos (meaning “gleaming” or “silvery” and referring to its blue-green color, which can vary from bluish green to olive green). The chemical formula of glauconite is K_0.08R¹_1.33R²_0.67[(Al_0.13Si_3.87O₁₀](OH)_2.

The sands containing glauconite can be found in sedimentary deposits along Mediterranean coasts, on sandstone areas near shore, etc. In Europe, the mineral has been used as an oil paint, especially in Russian icon paintings.

In my Atlas of Sands you can find glauconite in samples from two Dutch regions: Groningen (sample no 0636) and Zeeland (sample no 521). The photo above represents the sample no 436, originating from a sand excavation in France (Maisse, Essone region). However, I am not sure about its content in glauconite, despite the beautiful green color displayed.

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Additional info on glauconite:
See the complete mineral fact sheet at Mindat database.