عقیق احمر

Carnelian / Sard
Polished carnelian/sard pebbles. Scale is in millimeters.
General
Category	Chalcedony variety
Chemical formula	Silica (silicon dioxide, SiO2)
Identification
Molar mass	60 g / mol
Color	Reddish-brown
Crystal system	Trigonal
Cleavage	Absent
Fracture	Uneven, splintery, conchoidal
Mohs scale hardness	6 - 7
Luster	Vitreous, dull, greasy, silky
Streak	White
Diaphaneity	Translucent
Specific gravity	2.59 - 2.61
References