Chert / Flint
Quartz var. Chert · Mineral Specimen / Sedimentary Rock
Crystal System
Trigonal (Microcrystalline / Cryptocrystalline Quartz)
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2
Formation Process
Sedimentary process involving the chemical precipitation of silica from seawater or the replacement of calcium carbonate in limestone by silica-rich solutions.
About This Crystal
An opaque, dull-to-waxy, brownish-gray nodular mineral specimen with a rough, weathered exterior and a dense, microcrystalline internal structure.
Physical Characteristics
Brownish-gray body color, white streak, conchoidal fracture with sharp edges, no cleavage, specific gravity of approximately 2.60 to 2.65, brittle tenacity.
Optical Properties
Microcrystalline aggregate exhibiting aggregate birefringence, generally appearing dull with a waxy to vitreous luster on fresh conchoidal fracture surfaces.
Hardness & Durability
Origin Region
Found worldwide in chalk and limestone formations, particularly in the UK, US (Midwest and Texas), France, and North Africa.
Hardness & Durability
Mohs hardness of 7, making it quite durable and resistant to scratching, with good toughness due to its interlocking microcrystalline structure.
Care & Maintenance
Requires no special care; can be cleaned with warm soapy water and a soft brush, highly resistant to chemical attack and sunlight fading.
Rarity & Value
Very common globally, low commercial value unless fashioned into historical tools or high-grade decorative artifacts.
Special Characteristics
Famous historically for its ability to produce sparks when struck against steel, making it vital for ancient fire-starting and early firearms.
Lore & History
Used extensively by prehistoric humans across the globe for thousands of years to craft arrowheads, spear points, and cutting tools due to its sharp conchoidal fracture.