Greensand is formed under the sea and is often fossil rich. It was given it's name on account of it's noticable green grains. Greensand is a soft rock and often slumps.

Golf

Greensend rock does not exist. You are thinking of greensAnd rock - a sand or sediment having a dark greenish colour caused by the presence of glauconite. It can be fossil - rich.

Do you mean manganese? If so, a "greensand" filter might work - the cost was about $5000.00 around 10 years ago. It requires daily backwashing so you'd have to add the cost of the backwash water, if you're paying for it.

Greensand or Green sand is either a sand or sandstone, which has a greenish color. This term is specifically applied to shallow marinesediment, that contains noticeable quantities of rounded greenish grains. These grains are called glauconies and consist of a mixture of mixed-layer clay minerals, such as smectite and glauconite mica.