Amber and entombed insects

Amber is fossilized resin that blocks gaps in tree bark, especially conifers. It is not the same as sap, which transports nutrients through the heartwood of trees. Amber is very sticky and insects can be trapped in it when they try to burrow or eat the bark. When a tree limb is injured, amber can exude as blobs or drippings and flow down the side of the trunk. Insects can easily be engulfed or trapped in the resin, which commonly falls onto the ground and becomes incorporated into the soil. Other small animals, like lizards, frogs, birds, and even bats have been found in amber. Only a few tree resins (e.g., Kauri pine in New Zealand) can form fossilizable amber. Hardened resin is called copal, and it is easily transportable in streams and rivers, where is becomes part of the non-marine sedimentary record. In some cases, it can be transported into the nearshore-marine environment.

A polished specimen of copal (6 cm width);
 where collected unknown.

The transparency and color of the specimen shown above are typical for most amber. Bubbles, which are also commonly present, make amber lightweight and, in some cases, even floatable in water.

 

Left image: leaf (1 cm long) in specimen of copal shown above.

Right image: bug (7 mm, maximum length) in specimen of copal shown above; with wings and legs intact. 

Left image: Another polished chunk of copal (8 cm length, notice thumbnail--for scale--on left side of image); where collected unknown. Enlarged image shows a termite? (4 mm length) and below that, another insect, both found in the chunk.

These two pebbles, both polished, shown the typical range of color (hue) of most copal. The smallest piece is 1.5 cm in height. Both are from the Baltic Sea area, Denmark. No insects are present in these two specimens, which shows that not all copal has to have insects.

Copal is used in making jewelry and also in rosary beads. Copal is relatively soft, however, and can be scratched by a hard surface. When buying copal, the more insects (inclusions) present means that the price goes up. A word of caution: so-called "copal" can be made out of look-alike plastic.

The oldest known copal  is Late Paleozoic (Late Carboniferous, Pennsylvanian-age coal beds). The oldest copal with insects is Early Cretaceous (when the first flowering plants appeared).