Arrow 2 points to the conchoidal
fracturing of chert.
The prisms appear to lack internal subunits and fractures through individual prisms are conchoidal
rather than along specific planes.
These dykes are very fine-grained, hard, and locally display conchoidal
fractures and banding (Fig.
While the flakes share characteristics - such as sharp edges and conchoidal
fractures - with hominin stone tools, they are not used as such by the monkeys.
It was opaque black with a vitreous lustre and a surface that showed conchoidal
Essa rocha, que apresenta diferentes graus de friabilidade, e formada por areias de diferente granularidade que podem se encontrar cimentadas por processos diversos, as vezes por um cimento silicoso (arenito silicificado), outras por se encontrar em intercalacoes com o basalto da Formacao Serra Geral, situacao na qual se forma um quartzito de fratura conchoidal
(INSUGEO 2007; Grupo Consultor Mesopotamico 2006-2009; Remesal y Chavez 2014).
Silcretes are brittle, often with a lustrous conchoidal
fracture, and very resistant to weathering.
In addition, black, fine-grained, conchoidal
rocks are common in archaeological contexts in the Mackenzie Valley, and qualitative visual comparison of rock types is susceptible to observer error (cf.
03% maximum aluminum content to avoid conchoidal
fracture of the test specimens.
FRACTURE SCALE: l=premature(planar)fracture; 2=uneven; 3=poor conchoidal
; 4=medium conchoidal
; 5=good conchoidal
SEM images indicate a high degree of conchoidal
fracturing, possible triple point morphology typical of tripoli, and particle sizes ranging from 10-30 microns.
The best quality were deemed to be of French or English origin, translucent with a smooth surface of a "uniform tint of light yellow or brown color, and slightly conchoidal