Liberia ^ 



granuiites, amphibolite {hornblende)^ granites ^pegmatites ^ a.nd guartz 

 veins, together with the various products of the decomposition 

 of the above-named rocks. There is laterite overlying much 

 of the coast regions. Mr, Benjamin Anderson, who explored 

 the north-western parts of Liberia at the end of the 'sixties, 

 records that the rocks on the verge of the Mandingo Plateau 

 were mostly quartz and granite^ while the decomposed granite 

 produced that red ferruginous clay so familiar to all who have 

 seen the parklands of tropical Africa. This clay of decomposed 

 granite is strewn with round quartz pebbles. 



The promontory of Cape Mount is mainly of gabbro ^ 

 formation, sprinkled with the same quartz pebbles. Gabbro is 

 also seen in parts of the headland of Mesurado; for a considerable 

 distance inland behind Cape Mount the formation is granite 

 capped with rotten ironstone. Heavy black sand is very common 

 here, according to Captain Scarvell Cape. The same explorer, 

 who visited Western Liberia in 1903, describes the formation 

 near the Lofa River about fifty miles inland as being clay-slates^ 

 diorite^ and ironstone. He thought in the country between the 

 Lofa and the Mano Rivers tin might be discovered. The rock 

 about the lower rapids of the St. Paul's River is amphibolite (a 

 form of hornblende')^ and here, as in many of the stream valleys 

 of Liberia, are beautiful translucent quartz crystals which over 

 and over again are mistaken by the Americo-Liberians for 

 diamonds. Some of these quartz crystals are so hard that they 

 will scratch, if not cut, glass, and their appearance, with their 

 regular facets, often of hexagonal shape, is certainly very like 

 that of a rough diamond. The present writer has obtained 

 these same quartz crystals on the top of Mount Mlanje in 



' Gabbro is a compound Archaean rock composed of triclinic felspar and 

 diallage, sometimes mixed with olivine or hornblende (both of these last being 

 silicates of magnesium), quartz, magnetic iron and apatite (phosphate of lime). 



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