Jasper is an opaque form of Chalcedony - a microcrystalline type of Quartz. There are many different types.
Usually found in massive form, rather than stalactitic, botryoidal or pebbles.
Jasper is usually found banded or multi-coloured.
Chemical Formula - SiO2 (silicon dioxide) with impurities like iron oxides and organic material
Mohs Hardness – 6.5-7