BH and 
eee ARCHEOLOGY IN BRITISH GUIANA 85 
Ongls 2c) 40 5CM 
Ficure 29.—Grinding tools from the Mabaruma Phase. a-b, Metates. c, Mano fragment. 
high polish from use usually occurs only on the rounded edges in 
small areas not exceeding 0.5 by 1.5 cm. in diameter. 
Flakes and natural rocks—The percussion-struck flakes and frag- 
ments of unworked rocks from the various levels of each stratigraphic 
excavation and the surface collections were classified by rock material 
(Appendix, table 2). The most significant result of this analysis is 
the different popularity of certain rock materials in the Mabaruma 
Phase in contrast to the Alaka Phase (Appendix, table 1), although 
the two occupy the same geographical region. Whereas in the Alaka 
Phase the predominant material was andesite, this is rarely used in 
the Mabaruma Phase. Limonite and hematite concretions, broken in 
various ways and used as tools or as rubbing stones in the Alaka 
Phase, were also rarely used in the Mabaruma Phase. The most 
common rock material regardless of tool type in the Mabaruma Phase 
is a very fine-grained, micaceous schist. The other rocks, listed in 
