Chrysoberyl

1039

mindat:1:1:1039:5

6da5ad8a-c850-4c6f-8dcf-2b1716b87698

Approved, 'Grandfathered' (first described prior to 1959)

1789

4.BA.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
B : Metal: Oxygen = 3:4 and similar
A : With small and medium-sized cations

7.2.9.1

7 : MULTIPLE OXIDES
2 : AB₂X₄

7.4.4

7 : Oxides and Hydroxides
4 : Oxides of Be, Mg and the alkaline earths

Vitreous

Transparent, Translucent

Green shades, emerald-green, greenish white, yellowish green, greenish brown, yellow, canary yellow, blue

may be raspberry-red under incandescent light when chromian; colorless, pale shades of yellow, green, or red in transmitted light. Green varieties usually exhibit a green hue of medium to high saturation owing to the trace amount of vanadium within the crystalline structure. The chemical results showed a very good correlation between Cr and V, and both of them are at a low level; Fe is responsible for the canary yellow color.[[1]]

White

8½ on Mohs scale

Brittle

Distinct/Good
Distinct on {110}, imperfect on {010}, poor on (001)

Irregular/Uneven, Conchoidal

3.75(1) g/cm³ (Measured)    3.69 g/cm³ (Calculated)

Biaxial (+)

n_α = 1.746 n_β = 1.748 n_γ = 1.756

Measured: 70° , Calculated: 72°

δ = 0.010

High

r > v

Visible

X = c = columbine-red
Y = b = orange-yellow
Z = a = emerald-green

Exhibits a bluish opalescence or chatoyancy, notably on {010}. Also asteriated with a cat's eye effect. Chatoyancy, or cat’s eye effect, which is brought on by parallel needle-like inclusions within the crystal structure, usually made of rutile or hematite. Due to the way these imperfections reflect light, a bright line that resembles a cat’s eye appears across the gemstone’s surface,

Al, Be, O - search for minerals with similar chemistry

Fe,Cr,Ti

Orthorhombic

mmm (2/m 2/m 2/m) - Dipyramidal

a = 5.481 Å, b = 9.415 Å, c = 4.428 Å

a:b:c = 0.582 : 1 : 0.47

228.50 ų (Calculated from Unit Cell)

8

Simple crystals usually tabular {001}; short prismatic [100] at times, or, less often, [001]. Striated on {001} parallel to [100]. Twinned crystals usually flattened perpendicular to the composition plane, and have a feather-like striation on {001}. Twinning forms six-rayed spoke-like aggregates.

Quartz occurs as an irregular and colorless grain within the chrysoberyl host without any intrinsically crystalline structure. All the quartz grains detected were distributed along the healed fractures, accompanied by mica and fluids, muscovite, graphite and calcite.
Many long needles are distributed in the samples, and unlike the short needles within the growth lines, these needles are somehow curved and much longer, up to 1–2 mm. They are arranged randomly and show good transparency.

Common on twin plane {130}. Both contact and penetration twins, frequently repeated and forming pseudohexagonal crystals as viewed along [001] with or without reentrant angles. Also flattened heart-shaped.

Space Group: P bnm

Radiation - Copper Kα

Data Set: Brazil 196

Data courtesy of RRUFF project at University of Arizona, used with permission.

Granite pegmatites.

ⓘ Brazil

No defined type material.

Delamétherie J C (1792) Observations et mémoires sur la physique, sur l’histoire naturelle, et sur les arts et métiers. Discours préliminaire. Observations sur la Physique, sur l’Histoire Naturelle et sur les Arts 40, 2-40

Electrical conductivity increases with temperature.

Before the blowpipe, unaffected.

Not affected by acids.

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

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