Is Amber Flammable? (A comprehensive overview)

Is Amber Flammable?

Yes, amber is flammable. Amber tends to burn slowly similarly to incense. Many amber produce fragrances when burned. Burning amber, by itself, is very unlikely to cause explosions.

All amber is composed, organic molecules. In most forms of amber those organic molecules have a high molar mass. Those molecules may sometimes be referred to as polymers. However, a polymer is a molecule in which a given unit is repeated, which is often not the case for the molecules in amber.

Nonetheless, organic molecules, polymers or not, are in most cases at least slightly flammable. And that is the case for a typical amber.

It is worth mentioning that there is a variety of amber imitations that are made of plastics. Those plastics will have different behavior than amber when subjected to heat or flames.

What is Amber? 

  • Amber is fossilized tree resin.
  • Amber is made of complex mixtures of organic molecules. And small amounts of inorganic substances.
  • Animals or plants may be preserved inside amber structures.
  • Amber takes millions of years to form.
  • Amber is usually found underneath the surface.
  • Not everything about the process by which amber is formed is known.
  • It is known that the process involves evaporation of low weight molecules.
  • The process of the formation of amber involves chemical reactions: mainly polymerization reactions, the formed polymers gradually confer the hardness of amber.
  • On the Mohs scale, the hardness of amber is usually within the range of 2.0 to 2.5.
  • Amber has a somewhat low density range of 1.0 to 1.1 g/cm3.
  • Amber is usually soluble in some organic solvents, inlding: ethanol (CH3CH2OH), chloroform (CHCl3) and diethyl ether ((CH3CH2)2O).
  • The tree resin that originates amber must fulfill a series prerequisites in order for it to withstand physical and biological phenomenons of nature over millions of years.

Amber Classes

Amber can be classified by its typical composition. The composition is a direct indicative of the plant species that originally produced the resin, millions of years ago.

In terms of chemical structure, what every amber has in common is that they are majorly composed of organic molecules. More specifically, organic molecules with large molar masses formed by the union of smaller molecules.

These large molecules can be referred to as polymers. The molecular units that build up to form these polymers vary depending on plant species that produced the resin millions of years ago.

Class I

Ambers in this class are the most abundantly found in the geosphere. The molecular structural features of amber in class I comprises carboxylic acids derived from the terpenoid labdatriene

This class is subdivided in the classes Ia, Ib and Ic.

Ia

The main characteristic of the molecules that compose ambers in this class is that they are very similar to communic acid or the succininc acid (also known as butanedioic acid or HOOCCH2CH2COOH).

By distillation of baltic ambers, 3 to 8% (in mass) of succinic acid is obtained. Hence the other name by which baltic amber is known, Succinite. Succinite has a hardness between 2 and 3 in the Mohs scale, puting Succinite on the top end of hardness for ambers.

Ib

Similar to class Ia, with the main difference being that the acid that is obtained by distillation of ambers in this class furnishes quiral communic acid instead of succinic acid .

Ic

The most abundant amber in this class is the Dominican amber. The main constituents of ambers in these classes are the carboxylic acids ozic and zanzibaric (which have the same chemical formula of communic acid but differ in the structural disposition of the atoms in the molecule of the acid). 

The Dominican amber is mostly transparent and contains fossil inclusions more often than ambers in the above mentioned classes.

Class II

Ambers categorized in class II have their resins with structural features like polymers of sesquiterpenoids hydrocarbons. Triterpenoids and di-sesquiterpenoids may also be present in smaller quantities. Ambers in this class are found in Utah and Indonesia.

Class III

The basic structure caracter of this class is polystyrene. Examples of amber  belonging in this class are some ambers from New Jersey and from Germany. The modern day resin with the closest characteristics would be Storax (also known as Styrax).

Class IV

The molecules that constitute ambers in the class IV are non polymeric, their structure specially resembles the sesquiterpenoid Cedrane molecule. Examples of ambers in this class have been found in Bovey-Tracey (England) and in Moravia (Czech Republic).

Class V

The basic structural features of molecules composing this class of amber is a non-polymeric diterpenoid carboxylic acid, (especially based on the abietane, pimarane and iso-pimarane carbon skeletons).

The closest known resin in the present day is Rosin.

Some Amber Imitations may be more Flammable than Natural Amber

Given the interests associated with natural amber, a series of imitations of amber exist. These imitations can be made from fairly safe materials or from highly dangerous materials.

Amber imitations can be divided into imitations made of synthetic and of natural products.

Synthetic Materials Used in the Production of Amber Imitations

Amber imitations made of synthetic materials are mostly made of synthetic polymers, which are mostly flammable. The exceptions are the imitations made of inorganic  materials, such as stained glass.

Below is a list of the synthetic materials used to make amber imitations.

  • Acetylcellulose – Derived from cellulose, it is slightly flammable. Nowadays, it is not commonly found in amber imitations.
  • Bakelite resin – It is a polymer formed from the polymerization reaction of phenols with formaldehydes. It can catch on fire.
  • Casein – A family of phosphoproteins. Casein is not flammable under normal circumstances.
  • Celluloid – An organic polymer derived from nitrocellulose and camphor. Celluloid is highly flammable.
  • Cellulose nitrate – A polymer obtained from cellulose and nitric acid. Cellulose nitrate is a highly flammable material. Given its danger, nitrate cellulose is rarely used in newly made amber imitations.
  • Galalith – A polymer derived from the reaction of formaldehyde with casein. This polymer is pretty much not flammable.
  • Epoxy novolac – A polymer derived from the epoxidation of novolak (polymer formed from 3-methylphenols and formaldehyde). This polymer used to be used in the fabrication of the ‘antique amber’. Epoxy novolac is slightly flammable.
  • Polyester – A widely used polymer. Its properties vary depending on the method of preparation. Polyester is used with styrenes to make the ‘Polish amber’. Polyester does not easily catch on fire.
  • Polyepoxides resins – Reactive and flammable polymers made up of epoxides monomers.
  • Polystyrene – This polymer may require relatively high heat depending on the density of the polymer. Once ignited polystyrene fire spreads quickly throughout the whole polymer.
  • Polymethylacrylate – A vinylic polymer, it is highly flammable and it releases toxic fumes if burned.
  • Polyethylene – A widely used plastic. The flammability depends on its density, but it is usually flammable.
  • Stained glass and other ceramic materials – Composed mainly of silicon and oxygen this material is not flammable.

Imitations Made from Tree Resins

As a general rule, all imitations made from tree resins are at least slightly flammable since they are mostly composed of organic molecules.

  • Kauri resin from Agathis australis trees in New Zealand. Amber imitations made from Kauri resin are usually slightly flammable.
  • African and colombian copals (subfossil resins, that is, resins that are relatively young) obtained from Leguminsae trees.

Conclusion

Ambers are indeed flammable, however they don’t pose an immediate danger of fire. They do not necessarily catch on fire promptly and when they do the fire produced does not cause immediate danger.

There is a great diversity of ambers and in many cases their composition is not obvious, given the complexity of the process to form them.

There are many different materials that are or were used to fabricate amber imitations. Many of the materials used in these fabrications are flammable or highly flammable. 

If one is not sure about the real composition of a given imitation of amber, it is recommended to be extra careful.

Frequently Asked Questions (FAQ): Is Amber Flammable?

Can fire burn amber?

Yes, fire can burn amber. Amber usually burns slowly and releases a heavy smoke that can have a pleasant aroma. The hazard of the smoke is often unknown, however there is no evidence that smoke from burning amber is toxic.

Can amber be heated?

If amber is heated, it may melt or even catch on fire.

How can you tell if it’s real amber?

One way to make a quick test is by trying to cause damage with a sharp object (e.g. a knife or fingernails) if a scratch appears it probably means that it is an amber imitation. That test alone is not enough to prove that it is a real amber, it will only indicate that it is fake. There are imitations that will pass this test. To be sure it is real amber, a specialist should be consulted.

What temperature does amber melt?

Amber will usually melt at 250 ºC or above. Precisely speaking, it depends on factors such as the composition of the amber and the physical conditions (is it scratched, is it damaged, has it been in contact with organic solvents).

Does real amber float?

For something to float in water it must be more dense than water. Many tree resins are less dense than water, and so they float. Amber density is usually within the 1 to 1.1 g/ml range, while water density is exactly 1 g/ml. That means that amber may or may not float in water.

Does amber feel like glass?

Real amber is soft in comparison with glass. In the Mohs scale regular bottle glass has a hardness of 6.5, amber stays in the range of 2.0 to 2.0 hardness in the same scale.

References

Poinar G.O., Poinar H.N., Cano R.J. (1994) DNA from Amber Inclusions. In: Herrmann B., Hummel S. (eds) Ancient DNA. Springer, New York, NY. https://doi.org/10.1007/978-1-4612-4318-2_6

Ken B. Anderson, R.E. Winans, R.E. Botto, The nature and fate of natural resins in the geosphere—II. Identification, classification and nomenclature of resinites, Organic Geochemistry, Volume 18, Issue 6, 1992, Pages 829-841.

https://doi.org/10.1016/0146-6380(92)90051-X

Bray, P.S., Anderson, K.B. The nature and fate of natural resins in the geosphere XIII: a probable pinaceous resin from the early Cretaceous (Barremian), Isle of Wight. Geochem Trans 9, 3 (2008). https://doi.org/10.1186/1467-4866-9-3

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