The distribution of mineral inclusions (crystals and silica grains) in the secondary xylem of 250 species representing 53 families of amazonian woods was investigated. Silica grains occur in about 36% of the species studied. They are most frequently found in the ray cells almost always are solitary while in the fibers and parenchyma cells are sometimes in crystalliferous chains. The crystals are frequently of prismatic type and only in one species (Scleronema micranthum) was found crystal of druse's type.
Amazonian woods; mineral inclusions; silica; crystals