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Hollandite  (inclusions in Quartz)
Current inventory:  0 gems
 

  
Hollandite is named for Dr. Thomas Henry Holland (1868-1947), Director of the Indian Geological Survey.

Discovered in 1906;   IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Ba(Mn⁴⁺,Mn²⁺)₈O₁₆

Barium Manganese Oxide

Molecular Weight:

852.99 gm

Composition:

Barium

12.88 %

Ba

14.38 %

BaO

Sodium

0.27 %

Na

0.36 %

Na₂O

Manganese

42.51 %

Mn

4.16 %

MnO / 62.17% MnO₃

Aluminum

0.63 %

Al

1.20 %

Al₂O₃

Iron

8.51 %

Fe

12.17 %

Fe₂O₃

Silicon

0.33 %

Sii

0.70 %

SiO₂

Lead

4.86 %

Pb

5.23 %

PbO

Oxygen

30.01 %

O

100.00 %

100.38 %

= TOTAL OXIDE

Classification

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/D.08-60

Nickel-Strunz 10th Ed. ID:

4.DK.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
K : With large (+- medium-sized) cations; tunnel structures

Related to:

Cryptomelane Group

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Crystals short prismatic with flat pyramidal termination, to several em; radial fibrous, massive.

Twinning:

Common on {101}

Physical Properties

Cleavage:

Distinct/Good, Prismatic

Tenacity:

Brittle

Moh's Hardness:

4.7 - 6.0; VHN = 488-560 || [001], 620-689 - [001] (100 g load)

Density:

4.95 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Black, Grayish Black to Silvery Gray

Transparency:

Opaque

Luster:

Metallic, Earthy (Dull)

Refractive Index:

R1-R2: (400) 31.3-37.7, (420) 31.2-37.4, (440) 31.1-37.1, (460) 30.5-36.5, (480) 29.7-35.9, (500) 29.1-35.0, (520) 28.5-34.2, (540) 27.8-33.1, (560) 27.1-32.2, (580) 26.6-31.5, (600) 26.3-30.9, (620) 26.1-30.4, (640) 25.8-30.0, (660) 25.6-29.5, (680) 25.3-29.0, (700) 25.0-28.4;  Biaxial

Birefringence:

0.000

Dispersion:

n/a

Pleochroism:

Weak

Anisotrophism:

Strong; color in reflected light: White

Occurances

Geological Setting:

A primary mineral in contact metamorphic manganese ores, and a secondary weathering product of earlier manganese-bearing minerals.

Common Associations:

Bixbyite, Braunite, Piemontite, other manganese oxides

Common Impurities:

Fe, Pb, K, Na

Type Locality:

Kajlidongri mine, Jhabua District, Madhya Pradesh, India

Year Discovered:

1906

View mineral photos:

Hollandite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Hollandite is a silvery-gray to black mineral composed of barium and manganese. It occurs as opaque crystals and massive material but the interest in this mineral in the gem trade is as inclusions in Quartz gems. It forms beautiful radiating black "stars" throughout quartz crystals coming from Madagascar. These well formed Quartz crystals are collected by mineral collectors and rarely faceted into gems prominantly diplaying the attractive Hollandite stars.

Hollandite is found in these locations: in India, at Kajlidongri and Sitapar, Chhindwara district, Madhya Pradesh; in the Nagpur and Balaghat districts, Maharashtra; at Banswara, Rajasthan; and elsewhere. From Sorharras, Ultevis, Sweden. In Norway, from Tangen, Hurdal. At Langenberg, Saxony, Germany. From Inken, Tiovine region, Morocco. In the USA, in the Artillery Mountains, Mohave County, and in the Apache mine, Sierra Ancha district, Gila County, Arizona. As fine inclusions in Quartz from Madagascar.
 

  
Hollandite gems for sale:

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