Christopher Columbus was the first European to land on the Island of the Dominican Republic. He took with him gifts and offerings which he hoped to trade and exchange with the native people. Amongst these items was a necklace of Baltic Amber, a gift which even in Europe would be highly prized for its rarity. It was with some surprise then that several of the items brought by the native Taino people to trade were pieces of amber.
It was very soon discovered that the Dominican Republic, one of the largest islands in the Archipelago of Greater Antilles, had its own amber deposits occurring in the central mountain ranges and it was also found washed up in the beds of streams and rivers. Patty Rice notes in her book ‘Amber - the Golden Gem of the Ages’ that J.G. Haddow wrote in 1891:
"At Santiago, in San Domingo, in the valley of the brook Acagua, amber pieces, some as large as the egg of a goose, reward the explorer. The Acagua brook carries away the amber from hills of marl which is rich in petrifactions, and bares a near resemblance to Miocene clay of the Vienna basin."
The Dominican Republic is now recognised as a major source of amber which has come to the fore in the scientific community during the last 50 years, although its existence has been known about for centuries.
The tree source of the Dominican Republic amber has been determined by George Poinar as Hymenaea protera a leguminous species of tree. The identification was made from inclusions found in this highly fossiliferous form of amber. The tree may have resembled the extant species Hymenaea verrucosa which is found on neighbouring islands and in East Africa.
The amber on the island generally occurs in layers of lignite or carbonaceous clay interspersed with beds of sandstone. The sequences are different for the various amber locations but generally these geological elements are always present.
The amber usually occurs as small fragments or small nodules usually no bigger than few centimetres across, although bigger pieces are found The biggest ever discovered weighing 18 pounds, but this size is the exception and not the rule.
The Dominican Republic occupies approximately 65% of the Eastern side of the island and Haiti the remainder.The amber is not distributed throughout the island, it is known to occur in one of the Northern Mountain ranges; the Cordillera Septentrional. It is also found near Cotui which is located near the centre of the island and in Bayaguana a low land region near Sabana.
A map here shows most of the locations of amber which is mined on the island.
The author is unclear if amber is commercially exploited on Haiti. Certainly no mention is made in any of the recent publications relating to the Dominican Republic amber and although it is known to exist the extent is unclear.
The mining of amber generally take the same form throughout the island. The amber can be found through land slips which occur on the steep mountain sides. The fossil resin occurs in lignitic beds which when located are dug out. If the amber extends deep into the side of the mountain shafts are dug by hand to follow the deposit.
In pictures the author has seen, the mines look perilously unsafe with miners operating sometimes 200 feet into the mountain itself and in some cases without the mine being sheared or reinforced. This point is perhaps worthy of consideration whenever we gaze upon samples of Dominican Republic amber.
The age of these deposits varies. The youngest originate from Cotui which has been estimated to be between 15-17 Million years old. The oldest amber is located in the Cordillera Septentrional and has been established as 30-40 million years old. A total time span of some 25 million years for all of the amber deposits. The majority therefore comes from the Oligocene and Miocene.
All of the deposits so far discovered on the island are thought to be secondary. That is to say the amber has been moved and re-deposited from its location where it was first laid down.
The Dominican Republic is the home of an unusually fluorescent form of amber. This variety is often referred to as ‘Blue Amber’. The blue is not a solid colour but can be more accurately described as an iridescence which comes and goes as the amber piece is turned in a favourable light. It appears sometimes like an oily sheen. In this way the blue colour can almost vanish and then return as the lights strikes the piece in a favourable manner. The author has seen one piece during his life which possessed a true permanent blue tone which was clearly present no matter what the light conditions. For the most part photographs of glowing pieces of blue amber are due to long exposures times on film under strong fluorescent lighting. Under most normal conditions the amber’s colour is not quite so pronounced. It is reported that the bluest amber originates from the Los Cacaos mine.
What causes the blue colour in amber is not fully understood. One proposed theory links the colour to the occurence of volcanic ash or dust which was present when the resin was first exuded from Hymenaea protera tree. Whether or not volcanic activity is responsible is open to debate but it is highly likely that some form of ‘contamination’ takes place at the time of the resin formation.
The specific gravity of Dominican Republic amber is between 1.04 and 1.08 with a hardness calibrated on Moh’s scale of between 1.5 and 2.
Dominican Republic amber is highly fossiliferous, much more so than the Baltic deposits. As an island the fossil record is particularly interesting as it provides an insight into the colonisation process which must have progressed throughout the West Indies. It can also provide evidence of speciasation which occurs much more rapidly under island conditions than on the main land.
The study of inclusions in Dominican Republic amber is in its infancy compared to the scientific studies of Baltic amber which has been progressing for nearly two hundred years. But scientists such as Dr George Poinar and Dr David Grimaldi have done extensive research on the inclusions discovered within these deposits and some of their work focuses solely upon this source.
From the study of inclusions, syninclusions(1), examples of parasitism(2) and phoresy(3) which are found in Dominican Republic amber, a picture is slowly beginning to build up of what the ancient amber forest must have been like. This picture continues to unfold.
(1) Syninclusion refers to the presence of more than one type of inclusion in a piece of amber from which can be drawn conclusions and assumptions about their relationship and environment in which they lived.
(2) Phoresy is the hitching of a ride by a mite or smaller insect on the body of a larger one for the purposes of dispersion or movement from one feeding site to another.
(3) Parasitism is the harmful relationship between one animal and another from which one draws benefit at the expense of the other and in some cases to the point at which death results.
Vertebrate and vertabrate related inclusions occur much more frequently in Dominican Republic amber than in the Baltic variety, though they are still exceedingly rare. Amongst these infrequent inclusions there have been found; sphaerodactyl and anole geckos, Eleuthrodactylus frogs, feathers from birds and the hairs from various mammals.
A rather interesting frog was discovered in amber on the island during 1996 which shed light on how colonisation progressed through the West Indies. It was also noted in this particular specimen that several additional leg bones were present, more than the frog must have possessed. It is speculated by scientists that the frog and the additional legs could have been dropped by a bird who may have been using a branch or tree overhanging an embalming pool of resin which received the dropped frog and leg bones and over millions of years became amber.
Readers who wish to learn more about the Dominican Republic Amber Deposits would be advised to read four books which each contain sections relating to this source, they are:
The author lives and works in United Kingdom and as such the Baltic sources dominate collections and studies. I have therefore included this section on my web site to counter the Baltic bias which I think is present on some of the other pages.
A useful Internet resource for Dominican Republic amber and purchasing samples of amber with inclusions is Amber Island.
