American Museum of Natural History




	For more than 11,000 years, people have collected, traded, carved, and examined amber; yet much about the substance remains a mystery. For example, no one is certain how amber manages to preserve the organisms entrapped in it (called "inclusions") so exquisitely. It is thought that terpenes, compounds that become linked as the resin hardens, help to preserve the inclusions by dehydrating the organisms and killing any bacteria that might cause decay. Moreover, the organisms' tissues do not shrink as they normally would during the dehydration process; as a result their cellular structure remains intact, making amber inclusions perfect for DNA study.


	Amber from the Cretaceous period, 65 to 140 million years ago, when the later dinosaurs flourished, offers some of the earliest glimpses of many life forms. During this period, flowering plants (now the dominant life form on earth) evolved along with bees, moths, and other symbiotic insects. Cretaceous amber, from extinct conifer trees, is brittle and fractures easily. Specimens of amber from the Cretaceous period can be found all over the world, with the largest deposit in Northern Russia. The Middle East has the oldest Cretaceous amber containing insects and other larger organisms. In Kuji, Japan, there are pieces of amber that are 85 million years old. The United States has several Cretaceous deposits, although only in New Jersey is amber found in appreciable quantities. Deposits there range in age from approximately 65 to 95 million years old.
	This drawing depicts one of the most important insect fossils, the oldest known bee, Trigona prisca, which is encapsulated in amber from New Jersey. Although it dates from 65 to 80 million years ago, this specimen belongs to a surprisingly recent evolutionary group, raising questions about the corresponding evolution of flowering plants.	The oldest known mushroom, Archaeomarasmius leggetti, found in 90- to 94-million-year-old amber from New Jersey.



	The world's largest amber deposits come from the shores of the Baltic Sea, where amber has been harvested, traded, and crafted into decorative objects for at least 13,000 years. The 400-square-mile Samland Peninsula alone has produced ninety percent of all the amber in Europe. Until the mid-nineteenth century, pieces of Baltic amber were collected primarily from beaches. Since the 1850s, when engineers began dredging and mining operations, millions of pounds of Baltic amber have been mined.
		A large piece of Baltic amber, left unpolished to show the natural fissures, with a necklace of polished amber beads.


	Twenty-three- to thirty-million-year-old amber from the Dominican Republic is prized for the diversity of inclusions it contains. Dominican amber is mined chiefly to the north and east of Santiago, where landslides reveal veins of lignite -- or blackened, fossilized wood -- which accompany amber deposits. Using shovels and machetes, the amber miners may burrow deep into mountains, sometimes forming tunnels 100 to 200 feet long. Slightly softer than Baltic amber, amber from the Dominican Republic was produced by a Hymenaea tree, a now-extinct tree of the legume family. Dominican amber occurs in several colors, including yellow and deep red, as well as the rarer blue and smoky green.
		The ant is a deep red because the body cavity is pyritized, a process that occurs when inclusions trapped close to the surface are exposed to minerals in the surrounding matrix.


	Among the dozens of major amber deposits scattered throughout the world, most are from the Tertiary period, which dates from 1.6 to 65 million years ago. The deposits vary in age, botanical origin, color, and composition, and occur on every continent except Antarctica. The largest piece of transparent amber in the world, which weighs 33.5 pounds, comes from northern Myanmar, and is 40 to 50 million years old. Sicilian amber -- deposits of which are much smaller -- is approximately 20 million years old. The largest North American deposit of Tertiary amber is in Arkansas.