Etymology and history

The name means "spotted or speckled stone", and is derived from Greek iaspis, (feminine noun) via a Semitic language (cf. Hebrew yashepheh, Akkadian yashupu), ultimately from Persian yashp.

Green jasper was used to make bow drills in Mehrgarh between 4th-5th millennium BCE.Kulke, Hermann & Rothermund, Dietmar (2004). A History of India. Routledge. 22. ISBN 0415329205. Jasper is known to have been a favourite gem in the ancient world; its name can be traced back in Hebrew, Assyrian, Persian, Greek and Latin. On Minoan Crete within present day Greece jasper was carved to produce seals circa 1800 BC based upon archaeological recoveries at the palace of Knossos.

The word yashepheh in the Masoretic text of Exodus 28:20, referring to a stone in the Hoshen, is thus reflected in the Septuagint by the word Iaspis, and usually translated into English as Jasper. Despite the most common form of Jasper being red, scholars think that the yashepheh here actually refers to a green form of Jasper - which was very rare, and so highly prized; the Greeks used Iaspis to refer to the green form, while the red form simply fell under the term Sard - which just means red. Rebbenu Bachya argues that this stone represents the tribe of Benjamin, but there is actually a wide range of views among traditional sources about which tribe the stone refers to.

It is described in the Book of Revelation (21:11) as follows: "It shone with the glory of God, and its brilliance was like that of a very precious jewel, like a jasper, clear as crystal."

Types of jasper

Jasper can appear as an opaque rock of shades of red due to mineral impurities. Patterns can arise from the formation process and from flow patterns in the sediment or volcanic ash that was saturated with silica to form jasper, yielding bands or swirls in the rock.

Jasper may be permeated by dendritic minerals providing the appearance of vegetative growths. The jasper may have been fractured and/or distorted after formation, later rebonding into discontinuous patterns or filling with another material. Heat or environmental factors may have created surface rinds (such as varnish) or interior stresses leading to fracturing.

A brown jasper that occurs as nodules in the Libyan desert and in the Nile valley is known as Egyptian jasper or Egyptian pebble.

Picture jaspers simultaneously exhibit several of these variations (such as banding, flow patterns, dendrites or color variations) resulting in what appear to be scenes or images in a cut section. Spherical flow patterns produce a distinctive orbicular appearance. Complex mixes of impurities produce color variations. Healed fractures produce brecciated jasper. Examples of this can be seen at Llanddwyn Island.