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Amblygonite
Current inventory:  2 gems
 

Chemistry:  LiAl(PO₄)(F,OH)

Discovered in 1818;   IMA status: Valid (pre-IMA; Grandfathered).
The name Amblygonite is from the Greek words ambly for blunt and goni for angle, referring to the fact that its cleavage angle slightly differs from 90°, distinguishing it from scapolite for which it was originally mistaken.

Classification

Mineral Classification:

Phosphates

Strunz 8th Ed. ID:

7/B.02-30

7 : Phosphates, Arsenates, Vanadates
B : Waterfree phosphates with unfamiliar anions F, Cl, O, OH. cations of very small size: Li, Be
02 : Amblygonite group, Griphite - Tavorite

Crystal Data

Crystallography:

Triclinic - Pinacoidal

Crystal Habit:

Crude crystals, typically equant with complex form development, to 1.5 m; massive.

Twinning:

On several laws, with microscopic polysynthetic twinning common.

Physical Properties

Cleavage:

[100] Perfect, [110] Good, [011] Distinct

Fracture:

Uneven

Tenacity:

Brittle

Moh's Hardness:

5.5 - 6.0

Density:

2.98- 3.11 (g/cm³)

Luminescence:

Non-fluorescent

Radioactivity:

Not Radioactive

Optical Properties

Color:

Milk-white, yellowish, beige, salmon-pink, greenish, bluish, grey

Transparency:

Transparent, Translucent

Luster:

Vitreous to Greasy, Pearly on good cleavages

Refractive Index:

1.578 - 1.613  Biaxial ( - )

Birefringence:

0.020 - 0.030

Dispersion:

r > v

Pleochroism:

None

Occurances

Geological Setting:

An uncommon accessory mineral in zoned granite pegmatites; in high-temperature tin veins and greisens.

Type Locality:

Chursdorf, Penig, Chemnitz, Saxony, Germany

Year Discovered:

1818

View mineral photos:

Amblygonite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Amblygonite is a beautiful gem usually pale straw yellow. Darker, more saturated "lemon" yellow gems are rarer and more highly prized. An extremely rare lilic colored Amblygonite comes from Karibib, Namibia. Amblygonite is very closely related to Montebrasite and varies only by optiacal property. Amblygonite is optically (-) and Montebrasite is optically (+). It may be that if many Amblygonite gems where retested, they may actually be Montebrasites. In general, it is thought that most yellow gems on the market are Amblygonite, and most colorless gems are Montebrasite, but this does not always hold true.
 

  
Amblygonite gems for sale: