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Hollandite  (inclusions in Quartz)
Current inventory:  0 gems
 

Hollandite inclusions in Quartz

  
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:

We have not photographed our Hollandite gems. Please check back soon.
 

 

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