by Barry Taylor
Jaspers are a silica rich, dense, opaque and cryptocrystalline variety of textural Chalcedony, the technical name for this is a tectosilicate, a type of quartz rich rock. Jaspers often exhibit a unique and amazing ornamental pattern, as you may expect there is a slight overlap with Agate. Some Jaspers are in fact sometimes also called Agate, the Death Valley Plume Agate/Jasper is an example. The colours are often strikingly vivid or they have amazing colour combinations, each piece will differ slightly, and every piece is therefore unique. With a hardness of between 6.5 and 7, all Jaspers are basically a silica
rich rock and thus will take a good polish, which enhances their features; they can be made into beautiful pendants, rings and necklaces. The Jaspers often possess specific features that are common to all the different pieces of Jasper from the same location. These features can help identify the regional source of many Jaspers and they often have location names. The rock type known as Jasper is also the Birthstone of the Sun Sign Virgo and it is the mystical stone for the month of October.
There are basically 3 types of jasper:-
1 Those of volcanic origin such as Rain forest Jasper, leopard Skin Jasper and Ocean Jasper, all exhibit spherules. Some of these Jaspers are considered to be the volcanic rock Rhyolite
2 Those Jaspers from a sedimentary origin have been altered at a later stage, having been impregnated with silica. The patterns and markings often look like landscape features, as can be clearly seen in Biggs Jasper, Picture Jasper and Deschutes Jasper.
3 Metamorphic rocks such as Picasso Marble can exhibit fractures and re-healing as part of the formation process.
Jaspers of Volcanic origin
There are several varieties of a class of Jasper that are collectively known as the Orbicular Jaspers. These include material such as the Leopard Skin Jaspers from Mexico where it is commercially mined, such is its popularity. There is a variety of orbicular Poppy Jasper from Guadalupe, here the fine red sprays seen around white crystal centres are possibly a Sagenite, Fine red sprays of fine spiky growth, radiate from a central feldspar rich crystal focus. There is also confusingly a different Poppy Jasper with more appropriately shaped red petal like growths occur again around a white centre, this is an increasingly rare material of orbicular structure, they are almost certainly of volcanic origin, and these Jaspers are found near Morgan Hill, California in southern USA.
Leopard Skin Jasper
This is also considered by some to be a classic silica rich volcanic rock, as along with the Poppy Jaspers the rock is again often referred to as a Rhyolite. Such is their popularity; they are commercially mined near to Aguas Calientes, Mexico.
This Jasper has also been fractured and re-healed, leaving obvious vein formations that split the Leopard Skin patterning.
This is a type of orbicular Rhyolite, usually with a dark green matrix that has patches or Feldspar and Orb like structures, this material is from Australia.
Jaspers of sedimentary origin
There is a type of Jasper that often looks just like a picture, or most often perhaps more as a painting, as a consiquence this stone is known as a Picture Jasper, most famously from Biggs (Biggs Jasper) in Washington State. Other striking similar materials are the Porcelain Jaspers found in Mexico and China. There is a unique example of a Plume Jasper, much like the Plume Agates but even more colourful, this was found in Death Valley in the USA. Nobody is allowed to collect from there any more as this is now a National Park and Federal Land. Apart from the heat which can easily kill you; there are always the other common hazards of Rattlesnakes, Scorpions and Black Widow Spiders, quite who would be brave enough to try and find this material in the face of such odds beggars belief.
This variety much like the above can also be found in many localities, Deschutes Jasper is one such Jasper from Oregon, USA and also a similar rock called Onwhee Jasper often has strange picture like characteristics. Many Picture Jaspers start life as a mudstone and are much later petrified by silica rich waters, maybe from nearby volcanic rocks such as those from China, here it is a welded volcanic ash, hence the circulating silica rich waters. Willow Creek Jasper is yet another variety of Picture Jasper that comes from Boise, Idaho, USA.
This Jasper has striking red patterns on a yellowish to bronze coloured background.
Fine black markings together with a sky blue background very often also presents a remarkable painted landscape impression, this material comes from Oregon, USA.
There are numerous other Jaspers that include Fossils even Dinosaur Bone that has been replaced by Silica, also there are Fossil Trees and even Fossil Shell deposits, more about these will follow in a later article.
This is yet another striking sedimentary Jasper from the Pilbara Region of Western Australia; this Jasper has a very striking angular red pattern on a yellowish white background, it is referred to technically as a Silicified Pelite.
This is actually a unique conglomerate that has many experts puzzled, because the individual flint pebbles are all separated by a thin layer of very fine sand and do not touch! Large pieces of this stone are found all over the area and it is often found in Churchyards, supposedly as some type of religious marker. It is found marking mystical tracks called “Lay Lines”, these are very ancient and are said to hold magical properties, very strange indeed.
Jaspers of Metamorphic origin
This unusual Jasper has a colourful variety that was only recently found as a beautiful multicoloured marble from China. This material is often referred to as Cherry Creek Jasper, or now more correctly as Red Creek Jasper. This Jasper is from a Marble Quarry, which is a Metamorphosed Limestone, the rock has been fractured by Violent Earth Movements and then metamorphosed by later burial at great depth and then fused back together.
This Jasper has a unique pattern of fine dark lines forming a mesh like structure on an often very colourful background. Asimilar material is the Pilbara Jasper that comes from Australia, other varieties of this picturesque polished stone also comes from various locations in the USA.