Obsidian does not have cleavage because of the way it forms. Obsidian is essentially nature's form of glass and so it has no regular or patterned crystal structure. Without that crystal structure, there is no cleavage.
Obsidian has a conchoidal fracture.
fracture
Silvers Cleavage Is Silver Doesn't Split .
talc's cleavage is perfect in one direction, basal.
Pure obsidian actually has a glassy texture (grain), with no discernible crystalline structure.
Lead does have cleavage. Specifically, lead-induced cleavage is an integral part of ribosomal RNAs, and performs at a neutral pH.
it has no cleavage but it does have fracture
2.6g
black-green
about 7 or 7.5 with Mohs scale, like Quartz.
potassiun feldspar, quartz, plagioclase feldspar,biotite, and amphibole.
cleavage....
Galena's cleavage is cubic.
Sulfur's cleavage is imperfect.
Silvers Cleavage Is Silver Doesn't Split .
Cobalt has a cleavage in three directions, forming a cube.
no cleavage
Show cleavage? What Cleavage? Not really
Muscovite has perfect basal cleavage, or book cleavage.