Brianyoungite | |
---|---|
![]() Brianyoungite from Germany | |
General | |
Category | Carbonate mineral |
Formula (repeating unit) | Zn3(CO3,SO4)(OH)4 [1] |
IMA symbol | Byo [2] |
Strunz classification | 5.BF.30 (10 ed) 5/C.01-105 (8 ed) |
Dana classification | 17.1.15 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | C2/m |
Unit cell | 15.724 Å, b = 6.256 Å, c = 5.427 Å; β = 90°; Z = 4 |
Identification | |
Color | White |
Crystal habit | Rosettes of thin blades, pseudo- orthorhombic with β close to 90° [3] |
Cleavage | Perfect on {100}, possible on {001} [3] [4] |
Mohs scale hardness | 2 to 2.5 |
Luster | Vitreous |
Streak | White |
Diaphaneity | Transparent to translucent |
Specific gravity | 3.93 to 4.09 |
Optical properties | Biaxial |
Refractive index | nω = 1.635, nε = 1.650 |
Birefringence | δ = 1.635 [5] |
Solubility | Readily soluble with effervescence in acids [3] |
Other characteristics | Non-fluorescent [3] |
References | [1] [6] [3] [4] [5] [7] |
Brianyoungite is a secondary zinc carbonate mineral. The Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA) classifies it as a carbonate with the formula Zn3(CO3)(OH)4, [1] but sulfate groups SO4 also occupy the carbonate CO3 positions, in the ratio of about one sulfate to three carbonates, [3] so other sources give the formula as Zn3(CO3,SO4)(OH)4, and Gaines et al. classify the mineral as a compound carbonate. [7] It is similar in appearance to hydrozincite, another zinc carbonate. [5] It was discovered in 1991 and designated IMA1991-053. [5] In 1993 it was named "brianyoungite" after Brian Young (born 1947), a field geologist with the British Geological Survey, who provided the first specimens. [4] [7]
The mineral occurs as tiny rosettes less than 100 μm across, composed of thin blades just one or two micrometers across, elongated parallel to the b crystal axis, and tapering to a sharp point. [3] The crystals are white and transparent to translucent, with a vitreous lustre and a white streak.
The mineral belongs in the orthorhombic crystal system, or the monoclinic with β (the angle between the a and c crystal axes) close to 90o. [3] The space group is unknown, but assumed to be either P21/m, P21 or P2221. [4] [5] The structure is similar to that of hydrozincite. [7] There are four formula units per unit cell (Z = 4) and the lengths of the sides of the unit cell are a = 15.724 Å, b = 6.256 Å and c = 5.427 Å. [3]
Brianyoungite is a soft mineral with Mohs hardness similar to halite, only 2 to 2+1⁄2 according to some sources, [6] [5] but others say that the hardness is not determinable. [3] [4] It is fairly dense, with specific gravity 3.93 to 4.09, similar to that of celestine. Cleavage is perfect perpendicular to the a crystal axis (perfect on {100}) and possible perpendicular to the c crystal axis (possible on {001}). [3] [4] It is readily soluble with effervescence in acids. [3]
The mineral is biaxial, with refractive indices nω = 1.635 and nε = 1.650 and maximum birefringence δ = 1.635. [5] It exhibits straight extinction. [3] It is not fluorescent. [3]
The type locality is the Bloomsberry Horse level of the Brownley Hill mine,
Nenthead, Alston Moor District, North Pennines, North and Western Region (Cumberland), Cumbria, England.
[5] The type material is conserved at the
Royal Museum of Scotland, Edinburgh, Scotland, 1992.17.1–8.
[4]
Brianyoungite occurs with
gypsum on rubbly
limestone in the
oxidised zone of Brownley Hill Mine, and on specimens from the nearby Smallcleugh mine.
[3] It may be a secondary post-mining mineral.
[6]
[4]
At the type locality it is associated with
gypsum,
smithsonite,
pyrite and
goethite.
[4]
Brianyoungite | |
---|---|
![]() Brianyoungite from Germany | |
General | |
Category | Carbonate mineral |
Formula (repeating unit) | Zn3(CO3,SO4)(OH)4 [1] |
IMA symbol | Byo [2] |
Strunz classification | 5.BF.30 (10 ed) 5/C.01-105 (8 ed) |
Dana classification | 17.1.15 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | C2/m |
Unit cell | 15.724 Å, b = 6.256 Å, c = 5.427 Å; β = 90°; Z = 4 |
Identification | |
Color | White |
Crystal habit | Rosettes of thin blades, pseudo- orthorhombic with β close to 90° [3] |
Cleavage | Perfect on {100}, possible on {001} [3] [4] |
Mohs scale hardness | 2 to 2.5 |
Luster | Vitreous |
Streak | White |
Diaphaneity | Transparent to translucent |
Specific gravity | 3.93 to 4.09 |
Optical properties | Biaxial |
Refractive index | nω = 1.635, nε = 1.650 |
Birefringence | δ = 1.635 [5] |
Solubility | Readily soluble with effervescence in acids [3] |
Other characteristics | Non-fluorescent [3] |
References | [1] [6] [3] [4] [5] [7] |
Brianyoungite is a secondary zinc carbonate mineral. The Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA) classifies it as a carbonate with the formula Zn3(CO3)(OH)4, [1] but sulfate groups SO4 also occupy the carbonate CO3 positions, in the ratio of about one sulfate to three carbonates, [3] so other sources give the formula as Zn3(CO3,SO4)(OH)4, and Gaines et al. classify the mineral as a compound carbonate. [7] It is similar in appearance to hydrozincite, another zinc carbonate. [5] It was discovered in 1991 and designated IMA1991-053. [5] In 1993 it was named "brianyoungite" after Brian Young (born 1947), a field geologist with the British Geological Survey, who provided the first specimens. [4] [7]
The mineral occurs as tiny rosettes less than 100 μm across, composed of thin blades just one or two micrometers across, elongated parallel to the b crystal axis, and tapering to a sharp point. [3] The crystals are white and transparent to translucent, with a vitreous lustre and a white streak.
The mineral belongs in the orthorhombic crystal system, or the monoclinic with β (the angle between the a and c crystal axes) close to 90o. [3] The space group is unknown, but assumed to be either P21/m, P21 or P2221. [4] [5] The structure is similar to that of hydrozincite. [7] There are four formula units per unit cell (Z = 4) and the lengths of the sides of the unit cell are a = 15.724 Å, b = 6.256 Å and c = 5.427 Å. [3]
Brianyoungite is a soft mineral with Mohs hardness similar to halite, only 2 to 2+1⁄2 according to some sources, [6] [5] but others say that the hardness is not determinable. [3] [4] It is fairly dense, with specific gravity 3.93 to 4.09, similar to that of celestine. Cleavage is perfect perpendicular to the a crystal axis (perfect on {100}) and possible perpendicular to the c crystal axis (possible on {001}). [3] [4] It is readily soluble with effervescence in acids. [3]
The mineral is biaxial, with refractive indices nω = 1.635 and nε = 1.650 and maximum birefringence δ = 1.635. [5] It exhibits straight extinction. [3] It is not fluorescent. [3]
The type locality is the Bloomsberry Horse level of the Brownley Hill mine,
Nenthead, Alston Moor District, North Pennines, North and Western Region (Cumberland), Cumbria, England.
[5] The type material is conserved at the
Royal Museum of Scotland, Edinburgh, Scotland, 1992.17.1–8.
[4]
Brianyoungite occurs with
gypsum on rubbly
limestone in the
oxidised zone of Brownley Hill Mine, and on specimens from the nearby Smallcleugh mine.
[3] It may be a secondary post-mining mineral.
[6]
[4]
At the type locality it is associated with
gypsum,
smithsonite,
pyrite and
goethite.
[4]