How do I identify Manganolangbeinite?

Manganolangbeinite can be identified by its hardness of 2.5 - 3 on the Mohs scale, Rose-red color. Look for these key characteristics when examining specimens.

What color is Manganolangbeinite?

Manganolangbeinite typically appears in Rose-red. Color can vary depending on impurities and formation conditions.

How hard is Manganolangbeinite?

Manganolangbeinite has a hardness of 2.5 - 3 on the Mohs scale. This makes it a soft mineral that can be scratched easily.

Manganolangbeinite

A variety of Minerals

What is Manganolangbeinite?

Langbeinites are a family of crystalline substances based on the structure of langbeinite with general formula M2M'2(SO4)3, where M is a large univalent cation (such as potassium, rubidium, caesium, or ammonium), and M' is a small divalent cation (for example, magnesium, calcium, manganese, iron, cobalt, nickel, copper, zinc or cadmium). The sulfate group, SO2−4, can be substituted by other tetrahedral anions with a double negative charge such as tetrafluoroberyllate (BeF2−4), selenate (SeO2−4), chromate (CrO2−4), molybdate (MoO2−4), or tungstates. Although monofluorophosphates are predicted, they have not been described. By redistributing charges other anions with the same shape such as phosphate also form langbeinite structures. In these the M' atom must have a greater charge to balance the extra three negative charges. At higher temperatures the crystal structure is cubic P213. However, the crystal structure may change to lower symmetries at lower temperatures, for example, P21, P1, or P212121. Usually this temperature is well below room temperature, but in a few cases the substance must be heated to acquire the cubic structure.

Manganolangbeinite Market Value Calculator

Estimate the market value of Manganolangbeinite using size, quality, and finish. This preview calculator is for quick context and is not a formal appraisal.

Manganolangbeinite Localities Map

See where Manganolangbeinite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.

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North ZoneCentral RidgeSouth Basin

Key Characteristics

Characteristics of Manganolangbeinite

Lanbeinite crystals can show ferroelectric or ferroelastic properties. Diammonium dicadmium sulfate identified by Jona and Pepinsky with a unit cell size of 10.35 Å becomes ferroelectric when the temperature drops below 95 K. The phase transition temperature is not fixed, and can vary depending on the crystal or history of temperature change. So for example the phase transition in diammonium dicadmium sulfate can occur between 89 and 95 K. Under pressure the highest phase transition temperature increases. ∂T/∂P = 0.0035 degrees/bar. At 824 bars there is a triple point with yet another transition diverging at a slope of ∂T/∂P = 0.103 degrees/bar. For dipotassium dimanganese sulfate pressure causes the transition to rise at the rate of 6.86 °C/kbar. The latent heat of the transition is 456 cal/mol. Dithallium dicadmium sulfate was shown to be ferroelectric in 1972. Dipotassium dicadmium sulfate is thermoluminescent with stronger outputs of light at 350 and 475 K. This light output can be boosted forty times with a trace amount of samarium. Dipotassium dimagnesium sulfate doped with dysprosium develops thermoluminescence and mechanoluminescence after being irradiated with gamma rays. Since gamma rays occur naturally, this radiation induced thermoluminescence can be used to date evaporites in which langbeinite can be a constituent. At higher temperatures the crystals take on cubic form, whereas at the lowest temperatures they can transform to an orthorhombic crystal group. For some types there are two more phases, and as the crystal is cooled it goes from cubic, to monoclinic, to triclinic to orthorhombic. This change to higher symmetry on cooling is very unusual in solids. For some langbeinites only the cubic form is known, but that may be because it has not been studied at low enough temperatures yet. Those that have three phase transitions go through these crystallographic point groups: P213 – P21 – P1 – P212121, whereas the single phase change crystals only have P213 – P212121. K2Cd2(SO4)3 has a transition temperature above room temperature, so that it is ferroelectric in standard conditions. The orthorhombic cell size is a=10.2082 Å, b=10.2837 Å, c=10.1661 Å. Where the crystals change phase there is a discontinuity in the heat capacity. The transitions may show thermal hysteresis. Different cations can be substituted so that for example K2Cd2(SO4)3 and Tl2Cd2(SO4)3 can form solid solutions for all ratios of thallium and potassium. Properties such as the phase transition temperature and unit cell sizes vary smoothly with the composition. Langbeinites containing transition metals can be coloured. For example, cobalt langbeinite shows a broad absorption around 555 nm due to the cobalt T1g(F)→T1g(P) electronic transition. The enthalpy of formation (ΔfHm) for solid (NH4)2Cd2(SO4)3 at 298.2 K is −3031.74±0.08 kJ/mol, and for K2Cd2(SO4)3 it is −3305.52±0.17 kJ/mol.

Composition of Manganolangbeinite

The crystal structures of langbeinites consist of a network of oxygen vertex-connected tetrahedral polyanions (such as sulfate) and distorted metal ion-oxygen octahedra. The unit cell contains four formula units. In the cubic form the tetrahedral anions are slightly rotated from the main crystal axes. When cooled, this rotation disappears and the tetrahedra align, resulting in lower energy as well as lower crystal symmetry.