MINERALOGY. 2©j 



This is of a whitifh yellow colour, 

 contains likewife a great deal of iron, 

 and has the fame quality with the for- 

 mer, to harden foon in water, when 

 mixed with mortar. This quality can- 

 not be owing to the iron alone, but 

 rather to fome particular modification 

 of it, occafioned by fome accidental 

 cauies, becaufe thefe varieties rarely 

 happen at any other places, except 

 where volcanos have been, or are yet- 

 in the neighbourhood. 



SECT. CCX. 



u Calx of iron, united with another un- 

 known earth, Ferrum calcifcrme terra 

 qua dam incognita in time mix turn. The 

 pungfien of the Swedes. 



This is alfo, though improperly, called 

 White Tingrains. Seel:, clxxxi. 



This refembles the garnet-ftone, 

 (St£t. lxix.) and the tin -grains ; is nearly 

 as heavy as pure tin ; very refractory in 

 the fire, and excefiively difficult to re- 

 duce to metal. Iron has, however, been 

 melted out of it to more than 30 per 

 cent. It is very difficultly diffolved by 

 borax and alcaline falts, but melts very 

 eafily with the microcofmic fait, giving 

 a black flag : And for this reafon, this 

 lafb mentioned fait muft be employed in 

 the experiments on this ftone. It is 

 found, 

 1 Solid and fine-grained. 



a> Reddifn or nefh- coloured. 



k Yellow. 



