Green amber? Blue Amber? On the color spectrumgreen and blue are very close, hence the reason for both colors must be the same. And every argument leads to the same conclusion, the same cause: heat. But at what point was the amber put under such intense heat?
To explain Blue Amber we might want to line out the general history of amber, according to the gospel of geology. Of course all points are either uncertain or still heavily debated, which comes to show just how little we really know about this fickle planet we call home.
Weeping Hymenaea Protera
It is generally accepted that a very large extinct tree known as the Hymenaea Protera is responsible for squeezing out these large amounts of resin. We know this from flower petals found inside the amber that compare to the still-growing Algorrobo tree, a great-great-grandson of the H. protera. Using the contemporary Algorrobo as an analogy we can establish an approximate whodunit. The roots and trunk exude a yellowish to red resin and form hard lumps which become buried in the soil at the tree base. Large amounts of that resin have been found, hardened into copal, and it is this copal that sometimes is sold as amber to the fleeceable tourists–but it is yet a far cry from the real deal.
As a matter of fact, it is unlikely that this copal would ever turn into amber, for the copal of the extinct H. protera needed to go through an odyssey that would have had Homer shake in his sandals.
It is interesting to note that Algorrobo do not bleed much unless struck by lightning. The assumption is that either lightning or a fire caused a whole forest to practically bleed to death and hemorrhage such large amounts of resin. Several unlucky creatures from various genus eventually got stuck in the gluey gunk and bought it right there. Little ash or other proof that there had been such a fire has been found in amber, but maybe Blue Amber is it. Maybe it was the heat of the fires that induced changes in the molecular structure, that later would cause the blue coloration? Pure speculation at this point. Onward in the odyssey.
For the copal to maintain its clear appearance and the enclosures therein, it had to be quickly protected from weather. That happened indeed, ironically thanks to the weather. Frequent rains washed the top soil around trees down-slope into lagoonal and coastal areas of the Comatillo Basin. This basin is believed to have been located in the northern part of what is now Hispaniola, and it would be logical to assume that the Hymenaea sprout along the hillsides and the copal washed into said lagoon. Copal floats in salt water, so the question is how it ended up at the bottom of the basin. Possible it was pulled down by attached soil or decayed wood after bobbing for a while in the sea and so sank into the deep-water deposits where it was more and more covered by layers of sand and lignite. This step of the process could not haven taken more then a few days.
The next step is calculated in millions of years.
16 to 20 million years ago, a shooting-from-the-hip estimate, amber was still called copal and the enclosed insects where just getting cozy in it. Hispaniola on the other hand was nonexistent. Most likely there was a whole series of smaller islands, created a few million years earlier by a massive head-on collision between the Caribbean and the North American tectonic plates. On one of these islands our above forest of ancient Algorrobo was flourishing. Let’s call this prehistoric island, oh say, Atlantis.
As the old real estate axiom says, it’s all in location, location, location. The Comatillo Basin was somewhere in the northern middle of Atlantis and seemingly the only location for copal to undergo its complete transformation into amber. Of course there are minor amber finds in Cuba and Puerto Rico, but for some reason only in the Comatillo Basin on Atlantis the circumstances were perfect.
As stated above, the copal had by now hit rock bottom and begun to dig, so to speak. It was going deeper into its marine environment, with tons of water pushing down as well as more and more debris accumulating atop. It is estimated that the copal went down up to 300 feet in depth, and it was down here that it finally began its diagenic changes. The depth and pressure practically baked the copal, until–ping!–it had fossilized into amber.
It is generally assumed that the blue coloration was caused by lava flowing over the location of these copal deposits, but we see from this model that that is unlikely.
Then maybe the heat from pressure and depth?
This heat certainly causes the copal to become amber in the first place, but had it also caused the blue coloration, then all of the amber would have to be blue.
After a few million years the tectonic plates, like an unhappy card player, had once again reshuffled. Up became down and down became up. Large parts of Atlantis began to–you know–disappear into the ocean, while other parts finally broke surface and headed for the sky. Due to the movements along the Hispaniola and Puerto Rico Fault, the bottom of the Comatillo Basin became mountain ranges, pushing the amber deposits into the clouds, still leaving in the middle of La Hispaniola the Septentrional Fault. This would explain why the soil in which amber is found contains planktonic and marine microorganisms, sea snails (see my blog on that) and sometimes even mollusks and other marine animals, fish teeth, even fossils of crocodiles, turtles and dugongs.
After rising out of the ocean, nature began to chew on the sea-bottom-turned-mountain-range. Rain, wind and even digging animals began to shape the ranges into what we know now as the Cordilleras Septentrional and Oriental. Dirt broke free and amber pieces were redeposited in rivers and other locations were they were at last found by first the native Taino Indians, and later by European explorers. Said exploiters, erm, explorers already knew amber from the Baltic and only ventured after gold, which is why little amber was mined for the first 500 years. But over time, that too changed.
The rest is still history in the making.
So why is it blue?
Recent discoveries and advanced hypotheses about the origin of amber such as the one by geologist Manuel A. Iturralde-Vennet lined out in the above paragraphs suggest that previous assumptions concerning Blue Amber may no longer apply. Volcanic activity on Hispaniola or Atlantis (of course I’m only kidding, but you can see why some Atlanteans insist on Hispaniola being said mythical place) had pretty much seized by the Miocene epoch, so the heat that caused the molecular changes must have a different origin. Common sense suggests the smoke and heat during the excretion of resin. This would also explain the lack of enclosures in Blue Amber, as well as the swirls of resin and pulverized fragments classical to Blue Amber because of repeated liquefaction of the copal.
Thus far the gospel of geology. Much of the above is an estimate of what is at this time humanly possible to evaluate. Perhaps in the future further questions as to the origin of Blue Amber, and indeed amber, will be answered. For now we can but only revere in the beauty that is this unique gem.