Quartz with Iron Oxide and Sulfide Matrix
Quartz var. Milky Quartz with Pyrite/Limonite · Mineral Specimen
Crystal System
Trigonal, massive or crystalline aggregate habit
Mineral Group
Silicates (Tectosilicates)
Chemical Formula
SiO2 with FeS2 and FeO(OH)·nH2O inclusions
Formation Process
Hydrothermal vein formation involving silica-rich aqueous solutions precipitating in rock fractures under moderate to high temperatures
About This Crystal
A rough, hand-sized mineral specimen exhibiting a mix of milky white crystalline quartz, dark gray or smoky patches, and prominent yellowish-brown iron oxide (limonite or goethite) staining along fractures and matrix boundaries. The luster ranges from vitreous on fresh quartz surfaces to earthy or dull on the oxidized matrix, with translucent to opaque transparency.
Physical Characteristics
Color includes milky white, gray, and yellow-brown; streak is white for quartz; cleavage is absent in quartz; fracture is conchoidal to uneven; specific gravity is approximately 2.65 for pure quartz; tenacity is brittle; exhibits piezoelectric properties.
Optical Properties
Refractive index ranges from 1.544 to 1.553; uniaxial positive optical character; birefringence is low (0.009); doubly refractive.
Hardness & Durability
Origin Region
Worldwide distribution; commonly found in hydrothermal vein deposits globally
Hardness & Durability
Mohs hardness of 7 for quartz, making it durable against scratching but susceptible to impact due to fractures; good wearability for protected jewelry settings.
Care & Maintenance
Can be cleaned with warm soapy water and a soft brush; avoid harsh acids or prolonged exposure to strong chemicals; store away from softer stones that it might scratch.
Rarity & Value
Common; value is generally low to moderate, determined mostly by aesthetics, size, and interesting matrix combinations rather than gemstone grade clarity.
Special Characteristics
Features iron oxide staining (limonite/rust) filling micro-fractures, giving it a characteristic golden-yellow contrast against the white and gray quartz body.
Lore & History
Quartz has been used historically by various ancient cultures for tools, ornaments, and spiritual rituals. In modern metaphysical practices, milky quartz and iron-stained quartz are often associated with clarity, purification, and grounding energies, though these are traditional beliefs and not scientifically validated.