Translucent warm orange, fiery sunset red, to brownish-red (sard).
Chemical formula
SiO₂ + Fe₂O₃ (Hematite/Iron Oxide sub-microscopic inclusions)
Chalcedony / Microcrystalline Quartz • Quartz (Chalcedony Aggregate)
Agate
Curved or angular concentric banding in translucent white, gray, amber, red, and blue-gray tones, as well as dendritic or moss-like manganese/iron inclusions.
SiO₂ (Microcrystalline fibrous silica with trace iron/manganese oxides)Mohs 6.5 – 7.0 Mohs
Mineralogical & Gemological Profile
| Mineral Family | Chalcedony / Microcrystalline Quartz |
|---|---|
| Mineral Species | Quartz (Chalcedony Aggregate) |
| Gemological Variety | Agate |
| Chemical Composition | SiO₂ (Microcrystalline fibrous silica with trace iron/manganese oxides) |
| Crystal System | Trigonal (Microcrystalline aggregate) |
| Mohs Hardness | 6.5 – 7.0 Mohs |
| Specific Gravity | 2.58 – 2.64 |
| Refractive Index | 1.530 – 1.540 (Spot reading) |
Color Characteristics & Optical Behavior
Curved or angular concentric banding in translucent white, gray, amber, red, and blue-gray tones, as well as dendritic or moss-like manganese/iron inclusions.
Geological Context & Pakistani / Global Localities
Forms by rhythmic silica deposition inside volcanic vesicles and sedimentary cavities.
Collector Interest & Rarity Factors
Collectors prize natural fortification banding, eye agates, and scenic dendritic plume formations.
Fine Jewelry Applications
Cabochons, signet rings, intaglio seals (Aqeeq), and artisan pendants.
Treatment Considerations & Disclosure
Because chalcedony is slightly porous, dyeing and sugar-acid heat treatment have been practiced since Roman times. FADI Gems clearly distinguishes natural-color agate from dyed stones.
Care & Cleaning Instructions
Clean with warm soapy water; avoid harsh household chemicals or porous stain exposure.
Traditional Meaning
Traditional Symbolism & Cultural Heritage
Deeply cherished across Islamic, Middle Eastern, and South Asian heritage (known as 'Aqeeq') for engraved signet rings symbolizing steadiness and dignity.
Note: Cultural and birthstone traditions are presented strictly as historical folklore, never as scientifically verified medical or metaphysical effects.
Chalcedony / Microcrystalline Quartz
Related Entries
Vivid apple green to mint green; unlike emerald or chrome chalcedony, its color comes from trace nickel rather...
Chemical formula
SiO₂ + Ni²⁺ (Nickel-bearing phyllosilicate/pimelite inclusions)
Deep forest-green semitranslucent to opaque chalcedony speckled with vivid crimson spots of iron oxide (hematite).
Chemical formula
SiO₂ + Chlorite/Amphibole (green) and Hematite (red spots)