Top Customer Reviews. Failure of an off-side windshield wiper blade resulted in an arc of light scratches on the glass of my concours-winning collector car. Ranging from almost-undetectable to 'can just feel them under my fingernail' the scratches caught the light and weren't going to pass muster at my next car show.
An obsidian rock is an extrusive igneous rock that forms when a volcano erupts and has no time to crystallize, so it has a glassy texture. Obsidian rocks are generally black i â¦ n color.o rock is completely impermeable, but some porous rocks like shale and pumice are mostly impermeable, because â¦ the pores are not interconnected, thus not allowing fluids or gases to pass through them. This is why shale makes a good cap-rock, and pumice floats instead of sinking. 2 people found this useful.
Obsidian was so named from its resemblance to a stone found in Ethiopia by Obsius. It was used in antiquity for amulets and necklaces. Obsidian is a naturally occurring volcanic glass. It is usually an opaque black or grey but may be yellow, red, greenish brown. Obsidian may have an iridescent sheen caused by inclusions. Obsidian is used for ornamental purposes and as a gemstone. Many colored glasses are sold as obsidian often claiming to be natural.