Bulka Bags are approx 0.7m3  and will cover approx 13-18sqm per bag depending on size of stone and depth .
 
We recommend working on approx 50mm coverage for decorative purposes.
 
20mm Black Bassalt is an angular 19/20mm hard stone suitable for a non organic mulch in flower beds, pathways, flower beds, with stepping stones, decorative area and quick coverage of sand in any area of the garden.
 
It is a very dark grey stone which is black when wet.  Put with a Limestone stepping stone for  a striking contrast or a charcoal stepping stone for a more subtle apperarance.
 
Any stone can be used as a mulch, and it is especially useful in windy areas or areas where you are not wanting the mulch to rot down and add organic matter to the soil over time. Stone is a long term solution that does not need topping up.
 
A thicker coverage will assist with weed prevention along with some weed mat before laying ( can also use cardboard or newspaper) and weed killer can be applied for further maintenace ( beware if you also have some plants in area)