Earth Record
Mineralogy and formation
Blizzard stone is a trade name for a specific gabbro (a coarse-grained mafic intrusive igneous rock) from the Sierra Nevada region. The rock formed deep underground when basaltic magma cooled slowly enough for large crystals to develop. The "blizzard" appearance comes from white plagioclase feldspar spots (snowflake-like inclusions) against a dark matrix of pyroxene and biotite. Gabbro is the plutonic equivalent of basalt: same composition, slower cooling.
The white feldspar crystallized first as the melt dropped below about 1,100°C, then the darker minerals filled the spaces between. The resulting texture records a specific cooling sequence frozen in time.
Not Applicable (Aggregate Rock, Not A Single Crystal). Individual Constituent Minerals Have Their Own Crystal Systems: Plagioclase (Triclinic), Pyroxene (Monoclinic), Olivine (Orthorhombic). structure
Chemical FormulaComplex silicate; no single formula. Gabbro is a plutonic igneous rock composed primarily of calcium-rich plagioclase feldspar (typically labradorite-bytownite, CaAl2Si2O8) and clinopyroxene (augite, (Ca,Mg,Fe)2Si2O6), with variable amounts of olivine, orthopyroxene (hypersthene), hornblende, biotite, and magnetite/ilmenite as accessory minerals.Crystal SystemNot Applicable (Aggregate Rock, Not A Single Crystal). Individual Constituent Minerals Have Their Own Crystal Systems: Plagioclase (Triclinic), Pyroxene (Monoclinic), Olivine (Orthorhombic).Mohs Hardness6Specific Gravity2.7-3.3LusterDull to vitreous on fresh surfaces; takes a good polish revealing speckled black-and-white patternColorBlack-WhiteIMA StatusrockIMA NumberNone (rock, not approved mineral species) USA (Alaska)
Telling it apart
Blizzard stone is a trade name for a spotted black and white rock, and the fundamental problem is that sellers present it as a unique crystal species when it is actually a gabbro, an igneous aggregate of feldspar and dark mafic minerals. Other names for the same or similar material include indigo gabbro and mystic merlinite, and none of these are mineral species names. The rock contains plagioclase feldspar, pyroxene, and sometimes olivine or magnetite, so its hardness varies across the surface depending on which mineral the tool contacts.
It will not test as one single hardness the way quartz or tourmaline would. Genuine blizzard stone usually shows a speckled black and white to gray pattern in dense, heavy rock with a specific gravity higher than average due to the mafic minerals. If the seller lists it alongside mineral species crystals and prices it as a rarity, that is a labeling problem. Knowing it is a gabbro means understanding it is common, hard, and geologically interesting for what it teaches about igneous cooling, not for a fantasy identity.
Spotting the real thing
Blizzard stone is a trade name for a specific gabbro. Not a single mineral; an igneous rock composed of feldspar and pyroxene. White spots in dark matrix.
Specific gravity 2. 7-3. 3.
Takes a good polish. Verification is primarily about confirming it is the correct rock type (gabbro, not granite or diorite) from the claimed Alaska locality.
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