Gemstone profile and identification guide

Phosphosiderite

Phosphosiderite is a hydrated iron phosphate known for distinctive lilac to purple coloration.

3.75 Mohs Lilac, Purple Phosphate (Phosphosiderite)

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Overview

Phosphosiderite is a hydrated iron phosphate known for distinctive lilac to purple coloration.

Did you know? Phosphosiderite is often confused in trade with similarly colored phosphates.

Use this profile as a collector reference and educational guide for quick on-page comparison, then validate with the interactive identification system.

Identification

Name: Phosphosiderite

Scientific classification: Phosphate (Phosphosiderite)

Hardness: 3.75 Mohs

Transparency: translucent

Lustre: vitreous to silky

Crystal system: Monoclinic

Primary colour: Lilac

Secondary colour: Purple

Colour family: Purples

Lilac color and phosphate mineral context with low hardness are key indicators.

Verification Status

Status: verified-core-fields

Reference priority: GIA, Gem-A, Mindat, International Gem Society

Core identity, locality, and physical-property fields reviewed against standard gemological references.

Values are reported as practical gemological ranges where appropriate.

Physical Properties

Hardness category: medium

Hardness value: 3.75 Mohs

Chemical composition: Hydrated iron phosphate (FePO4.2H2O)

Crystal system: Monoclinic

Common locations: Peru, Chile, Argentina, Germany

Learn more: Gem-A gemstone education resources.

Colour Variations

Opaque to translucent lilac-purple hydrated iron phosphate.

Optical effects: None specified in the current dataset.

Detailed Gemology

Mineral species: Phosphosiderite

Mineral group: Phosphate group

Chemical formula: Hydrated iron phosphate (FePO4.2H2O)

Mohs hardness: 3.75

Crystal system: Monoclinic

Lustre: vitreous to silky

Transparency: translucent

Streak: White

Cleavage: Perfect in one direction

Fracture: Uneven

Specific gravity: 2.76-2.95

Refractive index: 1.59-1.63

Optical phenomena: None typically diagnostic

Colour range: Lilac, purple, pink-violet

Common inclusions: Matrix remnants, fracture veils

Geological environment: Oxidized phosphate deposits

Principal mining regions: Peru, Chile, Argentina, Germany

Important commercial sources: Commercial phosphosiderite for lapidary use is chiefly associated with South American phosphate deposits

Historical significance: A niche collector and lapidary phosphate gemstone.

Common treatments: Stabilization may be used.

Synthetic or imitation forms: Dyed stones and composites can imitate it.

Common look-alikes: Lepidolite, sugilite, dyed howlite

Jewellery uses: Used in cabochons, beads, and collector mineral pieces.

Care recommendations: Soft and fragile relative to common gems; avoid abrasion, chemicals, and ultrasonic cleaning.

Cross-check profile data with GIA Gem Encyclopedia and Mindat entry for Phosphosiderite.

Formation

Forms in the oxidation zones of phosphate-rich deposits.

Origin

Commercial phosphosiderite for lapidary use is chiefly associated with South American phosphate deposits

Uses

Best for: Used in cabochons, beads, and collector mineral pieces.

Ideal uses: Protected jewelry settings and collector cabochons.

Care

Soft and fragile relative to common gems; avoid abrasion, chemicals, and ultrasonic cleaning.

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