Amber fracture

Here we describe AFM results, which, in combination with X-ray photoelectron spectroscopy (XPS) data, support the notion that the macromolecular network of amber can be resolved with subnanometer resolution. Amber samples of 4x5x6 mm were cut from a big piece of Baltic amber, fractured by means of a metal wedge (Figure 19.7), mounted on the sample holder, and immediately transferred into the UHV chamber, in which the AFM measurements were carried out at a pressure of 3.5 x 10 mbar using loading forces of 2.5-3 nN. No obvious modifications of the surface structure could be detected within the scaimed areas upon repetitive imaging. For experimental details, see Ref. [97]. 

It occurs in irregular masses showing a conchoidal fracture. Hardness, 2,25 sp gr, 1.09 luster, resinous color, yellow to reddish or brownish it may be cloudy. Some varieties will exhibit fluorescence. Amber is transparent to translucent, melts between 250 and 300°C. 

Properties Yellow or amber amorphous lumps of brittle fracture. Sp. gr. 1.08. Melts readily on heating to 100-140°. Gives off inflammable vapors when heated. 

Rumanite came from the Carpathian Mountains in Romania. Both Tertiary and Cretacious deposits have been found. Although never plentiftil, it was immensely popular about 100 years ago, but today is seldom seen except in museums and, on rare occasions, in antique jewellery. It occurs in shades of brown, and is very clear except for the mass of small fractures within the material. This is very typical of rumanite and seldom seen in other ambers. 

Figure 1,21 Baltic amber cabachon owii with discoidal stress fracture (magnified).

F ure 1,22 Detail of discoidal stress fracture in Baltic amber. 

Conchoidal fracture The ridged or shell-shaped pattern which occurs when some materials break, e.g. amber or jet. 

Reflected light Light which is reflected at the surface of a specimen, or from an internal fracture (e.g. sun spangles in amber). 

Pale yellow to amber, translucent fragments brittle fracture at ordinary temp slight turpentine odor and taste. Readily fusible when heated, d 1.07-1.09. Add no. not less than 150. Insol in water. Freely sol in ale, benzene, ether, glacial acetic add, oils, carbon disulfide also so] in djl coins or fixed alkali hydroxides. 

Figure 19.28 AFM images of different size, nameiy, (a) SOOxSOOnm and (b) 200 x 200 nm of a fracture surface of Baltic amber and reiated height profiies (From Ref. [97]).

Figure 19.29 High-resolution AFM image of a fracture surface of Baltic amber (3 nN) image 7x7 nm. The arrows point to some supposed aromatic rings of diameter 0.28 nm (zoom in) (From Ref [97]).

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