Chemical composition -- An organic gem material,
amber is the fossilized resin of pine trees that lived some 30 million
years ago. Copal is a more
recent fossil resin; its properties are very similar, but it is more
readily attacked by solvents.
Color -- usually shades of yellow, brown, or
red.
Optics -- Singly refractive. R.I.
about 1.54. Typically displays internal stress patterns under a polariscope.
Durability -- very soft,
hardness about 2 to 2.5.
Crystal structure -- amorphous.
Specific Gravity -- very low, about 1.05-1.096. Amber will usually float in a saturated solution of salt water, unlike most of its simulants, such as plastic.
The thermal conductivity of amber is low, so it feels warmer to
the touch than non-organic gem materials.
If touched by a hot needle, amber releases a sweet, resinous odor.
In contrast, plastic substitutes have an acrid odor.
Amber is particularly prized when it contains intact fossilized
insects. If the insects are large and well formed and the amber
is attractively colored and relatively free from other faults,
it can command substantial prices.
Sources -- include the region around the Baltic Sea and the Dominican
Republic, but it occurs in many other locales.
Recent news reports indicate that one researcher says he has successfully
revived numerous strains of ancient bacteria trapped in amber!
The May 29, 1995, issue of Newsweek (p. 69) described
how microbiologist Raul Cano of California Polytechnic
State University claims to have revived 25 million year old Bacillus
bacteria from the guts of bees trapped in ancient amber. Shades
of Jurassic Park!