A mineraloid is a mineral-like substance that does not demonstrate crystallinity. Mineraloids possess chemical compositions that vary beyond the generally accepted ranges for specific minerals. For example, obsidian is an amorphous glass and not a crystal. Jet is derived from decaying wood under extreme pressure. Opal is another mineraloid because of its non-crystalline nature. Pearl, considered by some[who?] to be a mineral because of the presence of calcium carbonate crystals within its structure, would be better considered a mineraloid because the crystals are bonded by an organic material, and there is no definite proportion of the components.

Amber is fossilized tree resin, which has been appreciated for its color and natural beauty since Neolithic times.[2] Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects.[3] Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry.

There are five classes of amber, defined on the basis of their chemical constituents. Because it originates as a soft, sticky tree resin, amber sometimes contains animal and plant material as inclusions.[4] Amber occurring in coal seams is also called resinite, and the term ambrite is applied to that found specifically within New Zealand coal seams

Earlier[13] Pliny says that a large island of three days' sail from the Scythian coast called Balcia by Xenophon of Lampsacus, author of a fanciful travel book in Greek, is called Basilia by Pytheas. It is generally understood to be the same as Abalus. Based on the amber, the island could have been Heligoland, Zealand, the shores of Bay of Gdansk, the Sambia Peninsula or the Curonian Lagoon, which were historically the richest sources of amber in northern Europe. It is assumed that there were well-established trade routes for amber connecting the Baltic with the Mediterranean (known as the "Amber Road"). Pliny states explicitly that the Germans export amber to Pannonia, from where it was traded further abroad by the Veneti. The ancient Italic peoples of southern Italy were working amber, the most important examples are on display at the National Archaeological Museum of Siritide to Matera. Amber used in antiquity as at Mycenae and in the prehistory of the Mediterranean comes from deposits of Sicily.

He also states that amber is also found in Egypt and in India, and he even refers to the electrostatic properties of amber, by saying that "in Syria the women make the whorls of their spindles of this substance, and give it the name of harpax [from ??????, "to drag"] from the circumstance that it attracts leaves towards it, chaff, and the light fringe of tissues."

Pliny says that the German name of amber was gl?sum, "for which reason the Romans, when Germanicus C?sar commanded the fleet in those parts, gave to one of these islands the name of Gl?saria, which by the barbarians was known as Austeravia". This is confirmed by the recorded Old High German glas and Old English gl?r for "amber" (c.f. glass). In Middle Low German, amber was known as berne-, barn-, b?rnst?n. The Low German term became dominant also in High German by the 18th century, thus modern German Bernstein besides Dutch Dutch barnsteen.

Molecular polymerization, resulting from high pressures and temperatures produced by overlying sediment, transforms the resin first into copal. Sustained heat and pressure drives off terpenes and results in the formation of amber.[17]

For this to happen, the resin must be resistant to decay. Many trees produce resin, but in the majority of cases this deposit is broken down by physical and biological processes. Exposure to sunlight, rain, microorganisms (such as bacteria and fungi), and extreme temperatures tends to disintegrate resin. For resin to survive long enough to become amber, it must be resistant to such forces or be produced under conditions that exclude them

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