Types of Amber
Types of Amber
by Susie Ward Aber
One method of classifying amber is by color and degree of transparency. This criteria correlates to an optical classification of amber varieties. Colors of amber include yellow, orange, red, white, brown, green, bluish, and “black” (dark shades of other colors). The degree of transparency varies in amber from clear to cloudy. Clear amber is transparent and usually ranges from pale yellow to dark reddish yellow. Cloudy amber can be semi-transparent to opaque, a variety of colors and separated into terms such as fatty, bone (or osseous) or foamy (or frothy).
Fatty amber does not necessarily imply a green color. Fatty amber has tiny bubbles, suspended dust particles, and is usually a translucent, yellowish color resembling goose fat or also compared with the look of whipped honey. Green amber has tiny bubble inclusions and suspended particles, but it does not have the yellowish appearance of fat. The green color probably results from decaying organic matter in a marsh environment. Bone or osseous amber is whitish yellow or brown in color, opaque and looks similar to ivory or bone. Black decayed organic debris is commonly found in this type of amber. Foamy or frothy amber is very soft and therefore incapable of taking a polish. It is opaque and usually contains pyrite infilling cracks.
Other descriptive names for amber exist, reflecting not only color and degree of transparency but also chemical composition, the degree of weathering, places of discovery, workability, and functions in folk rituals. In Poland, some 200 folk names are applied to amber and some 80 variety names. “Soily” amber is described as brown or green, and full of gas bubbles and debris due to the decaying organic matter.
Another mode of classifying amber, a physical classification, is based on procurement, land or sea. Sea stone and scoopstone refers to amber found in or near the sea. Scoopstone is the amber gathered from seaweed. Sea stone or sea amber is collected as it is washed onto the beach or directly from the water (amber floats in salt water). Some amber procured on land is termed pit amber. Pit amber is mined from rock strata called “blue earth” and the source of most Baltic amber. This amber is covered with a crust, which obscures the quality of the piece. Sea amber is usually superior to mined amber because the waves provide polish, a uniform quality and there is no crust on the surface. Amber can also be found on land in secondary or alluvial deposits. Alluvial deposits indicate the material has been transported away from the primary source by erosional agents such as wind, water or glaciers.
Another physical classification system is the natural form in which amber is found. There are both external and internal tree trunk amber forms. External amber forms are the result of resin extruded by the trunk. This creates various shapes and sizes that can preserve trunk imprints as well as debris. Internal amber forms are the result of resin infilling fissures and extended wounds within the tree trunk. These casts (filling in a mold) can be large lumps or tiny, flat plates with imprints on both the convex and concave surfaces. The lumps can originate during the healing of wounds, such as broken branches, and the flat plates could be filling cracks or resin pockets between annual growth rings. One external dripping form can be termed a stalactite, elongate and conical, with a somewhat concentric structure resulting from multiple outpourings of resin. Internal crack filling forms can also be elongate, but the structure shows the axis is parallel to the direction of flow, not concentric.
Finally, amber can be classified based on chemical composition , usually as one of two fossil resins: succinite or retinite. Baltic amber or succinite was once thought to be the only “true” amber and is the most suitable for jewelry. Other fossil resins include gedanite, krantzite, beckerite, stantienite, glessite, schraufite and delatynite. These fossil resins are mostly devoid of inclusions and contain small amounts, if any, succinic acid. Gedanite is found with Baltic amber and thought to be resin from an extinct white pine species. It was first found near Gdansk, which is now in Poland but then called Gedania. Krantzite and gedanite are both rare varieties of Baltic amber, that is they contain some succinic acid, but both have lower hardness and other differing properties from Baltic amber or succinite. Beckerite is also found with Baltic amber, though nicknamed “brown resin”. Stantienite resembles beckerite in color but due to complete opacity it is termed “black resin”. These two types of amber are named for Becker and Stantien, two developers of amber dredging and mining operations in the Samland region in the 1800s.
