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LETTER XLII. 



VARIETIES OF PETRIFIED WOODS CONTINUED. ...THOSE PROCEED- 

 ING FROM THE OPERATIONS OF INSECTS. ...STARRY STONE OF 

 CHEMNITZ. ...TEREDO MARINA. 



AMONG the numerous subjects of the mineral kingdom, which 

 manifest traces of having derived their original forms from the 

 energies of vegetable life, there are none whose ambiguous appear- 

 ances occasion more perplexity, than the substances to which the 

 present Letter is chiefly appropriated, the STARRY STONE (staaren- 

 stein) OF CHEMNITZ. 



These stones, representations of which will be found in Plate 

 VIII. Fig. 1, 2, 3, &c. are chiefly found in the neighbourhood of 

 Chemnitz, and particularly near to Hillersdorf. Specimens of this 

 kind of stone have been said to have been also found near Belgrade : 

 and, in particular, one specimen has been mentioned, which was 

 reported to be one of the piles belonging to the bridge, which the 

 Romans had erected over the Danube. The general appearance of 

 most specimens of this stone convey the idea of its being fossil 

 wood; but those marks which dispose to this opinion, although most 

 evident in some, are, however, hardly, if at all, discoverable in 

 others. The hardness of these stones, in general, appears to be 

 nearly that of jasper, whilst in others it even seems to approach to 

 that of agate. The general colour of their ground is mostly of a 

 dark brown, sometimes inclining to a brick-dust red ; but, in dif- 

 ferent specimens, most of the common colours of fossil wood will 

 be found to form that of their several grounds. The circumstances, 

 however, which constitute the difference between these substances, 



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