hexagonal Cyclosilicates

Maxixe-type Beryl

Be3Al2Si6O18

Crystal Structure

CDL Notation

 #! Species: Maxixe-type Beryl (Be3Al2Si6O18; irradiated colour variety)
#! System: Hexagonal (6/mmm)
#! Habit: Prismatic hexagonal; deep navy-blue irradiation colour centre
hexagonal[6/mmm]:{10-10}@1.0 + {0001}@0.6

Crystal System hexagonal

Point Group 6/mmm

Crystal Forms (2)

{10-10} {0001}

Quick Facts

Hardness

7.5

Specific Gravity

2.68

Refractive Index

1.563

Optical Character

Uniaxial -

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Physical Properties

Crystal Systemhexagonal

Hardness (Mohs)7.5

Specific Gravity2.68

CleavageImperfect basal

FractureConchoidal

LustreVitreous

Optical Properties

Refractive Index1.563

Birefringence0.005-0.008

Optical CharacterUniaxial -

Dispersion0.014

Pleochroismstrong: Deep blue (ordinary ray) / Colourless to pale blue (extraordinary ray)

Colours

Deep navy to inky blue (much more saturated than aquamarine)

Localities

Brazil (Maxixe mine, Minas Gerais; type locality for naturally irradiated blue beryl; mostly exhausted)Russia (Ural; possible occurrence per Andersson 2011)Any beryl from any locality can produce Maxixe-type colour by artificial irradiation treatment

Common Inclusions

[object Object][object Object]

Known Treatments

The colour itself IS a treatment in commercially sold Maxixe-type (artificial irradiation of colourless or pale beryl)[object Object]

Crystal Forms

prismpinacoid

Diagnostic Features

Deep navy to inky blue much more saturated than aquamarine; strong dichroism deep blue/colourless (stronger than aquamarine blue-green/colourless); CRITICAL: colour FADES on prolonged light exposure (sunlight/UV) — aquamarine does NOT fade; absorption spectrum differs from aquamarine (CO3-related bands ~575, 610, 650-700 nm vs Fe2+ in aquamarine)

Notes

Irradiation-induced deep blue colour variety of beryl (Be3Al2Si6O18). Chemistry per VERIFIED.md conflict resolution F-01: correct cyclosilicate formula Be3Al2Si6O18 (NOT Be3Al2(SiO3)6). Colour centre: CO3^2- or NO3^- ions in beryl channels are irradiated to create the colour centre. NOT caused by Fe2+ (as in aquamarine). Confirmed by Adamo, Pavese et al. 2008, Gems & Gemology 44(3):214-226 (DOI 10.5741/gems.44.3.214) [VERIFIED via live API]: primary modern reference differentiating Maxixe-type from aquamarine and synthetic blue beryl. Also Andersson 2011, Journal of Gemmology 32(5):145 (DOI 10.15506/jog.2011.32.5.145) [VERIFIED]. Colour centre mechanism: Fritsch & Rossman 1988 (DOI 10.5741/gems.24.1.3) [VERIFIED]. CRITICAL TRADE ISSUE: Maxixe-type colour FADES upon prolonged light exposure (UV/sunlight). Aquamarine does NOT fade. This is the single most critical trade distinction. UV lamp test (24-48 hours): Maxixe-type shows noticeable fading; aquamarine unchanged. Disclosure as irradiated fading colour is mandatory. Store in dark; warn customer.