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Description
Answer
AKA Schorl; most widespread variety of tourmaline; coloration comes from iron
Black tourmaline
Complex silicate with inclusions; formed by rapid cooling lava; more like glass in structure than crystal; looks vary: can be translucent (Aka "Apache Tears"), can contain grey or white flecks ("snowflake"), or can be mahogany
Obsidian
Variety of agate comprising bands of quartz, chalcedony, and opal; comes from Greek work meaning "fingernail"; easily identifiable by the striking contrast of black and white bands
Onyx
Known as a pure iron oxide; known as lodestone when magnetized; single, octahedral crystals are common; tends to be more grainy with angular fractures
Magnetite
Seen to have fallen from space; varieties known: iron, stone, and pallasites; can be found anywhere it has fallen
Meteorite
Can be blue-grey; variety of quartz mixed with chalcedony; formed by silica rich shells and sea fungi laid down in ancient oceans; useful to ancient humans for weapons, tools, and for making fire when stricken
Flint
Has high iron content; tumbled stones are shiny, metallic, and heavy for their size; usually found naturally in rounded, kidney-shaped lumps; broken edges turn red when exposed to air
Haematite
Valued for thousands of years; epitomizes the moon; pure form is very soft and usually mixed into an alloy; used for jewelry, tooth fillings, and tableware; can cause Argyria if ingested
Silver
Found often in mountainous regions with volcanic rock - usually where granite exists; 'hazy' coloration is thought to occur when clear quartz is subjected to radioactive decay in nearby minerals; has various tints of brown
Smokey Quartz
Resembles bits of dried tar; definite origin is still unknown; varieties are named after where they are found; surfaces tend to be irregular and pitted; colours variation include: green and brown tints