# Geominerals/Boronides

Qingsongite is a rare boron nitride (BN) mineral with cubic crystalline form first described in 2009 for an occurrence as minute inclusions within chromite deposits in the Luobusa ophiolite in the Shannan Prefecture, Tibet Autonomous Region, China. It was recognized as a mineral in August 2013 by the International Mineralogical Association named after Chinese geologist Qingsong Fang (1939–2010).

## Aksaites

Aksaites have the formula Mg[B $_6$O $_7$(OH) $_6$] · 2H $_2$O, IMA symbol is Aks, IMA formula: MgB $_6$O $_7$(OH) $_6$ · 2H $_2$O.
Aksaite is orthorhombic.
"According to the results of the structural analysis, the largest thermal motion is shown by the water molecule, O(14), which is only linked to the Mg atom and to O(13") through a hydrogen bond. The thermal amplitude of two of the three triangular hydroxyls, O(11) and O(13), involved in a bond with boron as well as in two hydrogen bonds, is rather large. Much smaller is the displacement of the O(12) hydroxyl which is also participating to a bond with magnesium. It is also easy to understand the slight thermal motion of the water molecule O(15), which is involved in a bond with magnesium and in three hydrogen bonds as well."

## Barberiites

Barberiite has the formula NH $_4$(BF $_4$).

## Boraxes

Boron occurs primarily on Earth as an oxide, or borate, such as borax, imaged on the top right.
"Mineral subclasses apply to the borate and silicate classes, where the configuration and bonding of tetrahedra are used to group structurally similar minerals. The subclasses are: neso-, soro-, cyclo-, ino-, phyllo- and tectosilicates(borates). Traditionally the borates are divided into monoborates, diborates, triborates, tetraborates etc. (e.g. Strunz & Nickel, 2001), however, enough structural data is known to base classification of borates on the polymerisation of the borate anion."
"A critical building block for creating the first life on Earth was found in 3.8-billion-year-old rocks from Isua, Greenland, [...] For the first time, rich concentrations of the element boron have been found in Isua's ancient marine rocks [...] The discovery signals that boron was circulating in seawater and was absorbed by marine clays, which eventually became tourmaline [...] Boron can stabilize ribose, one of three key components of RNA. Ribose, an organic sugar molecule, has a short half-life and naturally decomposes without a stabilizer. [...] Until now, theories for the origin of RNA life pointed to RNA-based chemicals arriving on Earth from Mars. That's because Earth's first rocks and oceans seemed devoid of boron, which takes the form of borate minerals on Earth. On Mars, clays with boron and another RNA stabilizer, molybdenum, are abundant."
"I want to challenge this idea that the early ocean was borate free. The early ocean already contained borate, and therefore, early Earth — not Mars — could provide environments to stabilize ribose."
"The Isua rocks are among the oldest pieces of crust still around from Earth's earliest eons. The layers were deposited under a liquid water ocean, perhaps when life was first emerging. After billion of years of continental smashups, the rocks have been heated, faulted and folded, [...] Some of the rocks were seafloor sediments, such as mud and chert, and others were lavas erupted from underwater volcanic vents, such as pillow basalts. [The] boron in tiny tourmaline crystals trapped inside garnets in the ancient seafloor sediments. The garnets and tourmalines formed after the sediments were deposited, when the rocks were metamorphosed. Boron is one of the major elements of tourmaline. Isua's volcanic rocks also carry boron-rich tourmalines [...] Hydrothermal fluids circulating in the rocks are the likely source of the boron [...] Boron has two isotopes (elements with different numbers of neutrons in their nuclei). The boron isotope ratio in Isua's volcanic rocks also suggests early oceans carried enough boron to support RNA-based life".
"There could have been a role for boron in the stabilizing of ribose in the RNA origin of life. [...] boron-rich seawater [has been] cycling through the Isua volcanic rocks, despite a lack of continental crust. The tourmaline formed in an environment resembling today's deep-sea hydrothermal vents, where superheated seawater and other fluids spew from volcanic fractures. The abundant tourmalines indicate the fluids circulating through the ancient rocks were rich in boron. There is no convincing evidence of seawater boron concentrations being lower at 3.8 billion years ago than at the present."

## Clinometaborates

Clinometaborate has the formula HBO $_2$.

## Jadarites

Category: Nesosilicate with BO $_3$ triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO $_4$.
Formula: LiNaSiB $_3$O $_7$OH.
Molecular weight: 219.46 g/mol
Molecular Weight: 221.63 gm.
Strunz: 9.AJ.40.
System: Monoclinic.
Class: Prismatic (2/m) (same H-M symbol).
Symmetry: P2$_1$/n.
Cell Dimensions: a = 6.818, b = 13.794, c = 6.756, Z = 4; beta = 111.1° V = 592.78 Den(Calc)= 2.48.
Unit cell: a = 6.816(2), b = 13.789(2) c = 6.758(2) [Å]; β = 111.08(2)°; Z = 4.
Axial Ratios: a:b:c = 0.4942:1:0.4897.
Unit Cell V: 592.8 Å³.
Color: White.
Morphology: Massive aggregates, several meters thick. Individual subhedral (tabular, elongate) to anhedral crystals rarely exceed 5 - 10 μm in size. Platy habit..
Fracture: Irregular/Uneven to conchoidal.
Tenacity: Brittle.
Mohs: 4 - 5.
Luster: Dull.
Optical property = Biaxial.
Fluorescence: Weak pink to orange under UV.
Luminescence: Fluorescent, Short UV=weak pink orange, Long UV=weak pink orange.
Streak: White.
Gravity: 2.45.
Twinning: Exhibited by transmitted light in plates and grains in some crystallites.
Diaphaneity: Translucent to opaque.
Environment: Discovered in drill core. The Jadar Basin is composed of a sequence of oil-shales, dolomicrites and pyroclastic deposits of Neogene (Early to Middle Miocene) age. New structure type.
Jadarite is a white, earthy monoclinic silicate mineral, sodium lithium boron silicate hydroxide (LiNaSiB $_3$O $_7$(OH) or Na $_2$OLi $_2$O(SiO $_2$) $_2$(B $_2$O $_3$)3H $_2$O.

## Jimboites

Jimboite has the formula (Mn$^{2+}$ ,Mg) $_3$[BO $_3$] $_2$.

## Kernites

Kernite aka rasorite has the formula Na $_2$B $_4$O $_6$(OH) $_2$·3H $_2$O.
Kernite is soluble in cold water and alters to tincalconite when it dehydrates and undergoes a non-reversible alteration to metakernite (Na $_2$B $_4$O $_7$·5H $_2$O) when heated to above 100 °C.
The largest documented, single crystal of kernite measured 2.44 x 0.9 x 0.9 m$^3$ and weighed ~3.8 tons.

## Kotoites

Kotoite has the formula Mg $_3$[BO $_3$] $_2$.
Type Locality: North orebody (New orebody), Hol Kol Mine (Holgol; Suan; Namjong), Suan County, North Hwanghae Province, North Korea.
Geological Setting of Type Material: Contact metamorphic zone of a granitic intrusion into dolomite.
Associated Minerals at Type Locality: Szaibélyite, Spinel, Ludwigite, Forsterite, Fluoborite, Dolomite, Clinohumite..

## Metaborates

Metaborate has the formula HBO $_2$.
EC Number: 236-659-8.
CAS Number: 13460-51-0
Heating of boric acid at 80-100 °C releases water to give orthorhombic metaboric acid:
3 B(OH)$_3$ → (BOH)$_3$O$_3$ + 3 H$_2$O.
Upon heating at 130-140 °C in a sealed ampoule (to prevent dehydration), orthorhombic metaboric acid converts to the monoclinic form:
    (BOH)$_3$O$_3$ → B$_3$O$_4$(OH)(H$_2$O)
This material, called modification II, has a polymeric structure, and a higher melting point (201 °C) and density (2.045 g/cm$^3$). The structure of this species resembles its precursor except that the rings are connected and 1/3 of the boron centres are tetrahedral.
Above 140 °C, boric acid or the other forms of metaboric acid convert to cubic metaboric acid.
A number of metal borates are known, produced by treating boric acid or boron oxides with metal oxides, examples hereafter include< linear chains of 2, 3 or 4 trigonal BO$_3$ structural units, each sharing only one oxygen atom with adjacent unit(s):
* diborate [B$_2$O$_5$]$^{4−}$, found in Mg$_2$B$_2$O$_5$ (suanite),
* triborate [B$_3$O$_7$]$^{5−}$, found in CaAlB$_3$O$_7$ (johachidolite),
* tetraborate [B$_4$O$_9$]$^{6−}$, found in Li$_6$B$_4$O$_9$.
Metaborates, such as lithium metaborate (LiBO$_2$), contain chains of trigonal BO$_3$ structural units, each sharing two oxygen atoms with adjacent units, whereas Sodium metaborate (NaBO$_2$) and KBO$_2$ contain the cyclic [B$_3$O$_6$]$^{2−}$ ion.

## Nordenskiöldine

Nordenskiöldine has the formula CaSn$^{4+}$ (BO $_3$) $_2$.

## Qingsongites

Qingsongite is the only known boron mineral that is formed deep in the Earth's mantle. Associated minerals or phases include osbornite (titanium nitride), coesite, kyanite and amorphous carbon.

## Reedmergnerites

For the "reedmergnerite unit, BSi $_4$O $_{10}$ ... The spectra showed small amounts of it, and we saw no evidence of fragmentation (i.e., no corresponding smaller fragments that would appear to be constituents). Thus, it does not appear to be the dominant group in the glass network. ... The borate association remains dominant, however, even as we increase the soda content."

## Sassolites

Sassolite has the formula H $_3$BO $_3$, occurs in volcanic fumaroles and hot springs, as well as in bedded sedimentary evaporite deposits.

## Schorl

Chemical composition: NaFe$^{2+}$ $_3$Al $_6$Si $_6$O $_{18}$(BO $_3$) $_3$(OH) $_3$OH.
The most common species of tourmaline is schorl, the sodium iron (divalent) endmember of the group.
The first description of schorl with the name "schürl" and its occurrence (various tin mines in the Ore Mountains) was written by Johannes Mathesius (1504–1565) in 1562 under the title "Sarepta oder Bergpostill".
In the 19th century the names common schorl, schörl, schorl and iron tourmaline were the English words used for this mineral.

## Takedaites

Takedaite has the formula Ca $_3$[BO $_3$] $_2$.

## Tourmalines

Formula: (Ca,K,Na, vacancy defect ▢)(Al,Fe,Li,Mg,Mn) $_3$(Al,Cr, Fe,V) $_6$(BO $_3$) $_3$(Si,Al,B) $_6$O $_{18}$(OH,F) $_4$
* Category: Cyclosilicate.
* Crystal system: Trigonal.
* Crystal class: Ditrigonal pyramidal (3m). H-M symbol: (3m).
* Space group: R3m (no. 160).
* Crystal habit: Parallel and elongated. Acicular prisms, sometimes radiating. Massive. Scattered grains (in granite).
* Fracture: Uneven, small conchoidal, brittle.
* Tenacity: Brittle.
* Mohs scale hardness: 7.0–7.5.
* Luster: Vitreous, sometimes resinous.
* Streak: White.
* Diaphaneity: Translucent to opaque.
* Polish luster: Vitreous.
* Refractive index: n$_ω$ = 1.635–1.675 n$_ε$ = 1.610–1.650.
* Optical properties: Double refractive, uniaxial negative.
* Birefringence: −0.018 to −0.040; typically about −0.020 but in dark stones it may reach −0.040.
* Dispersion: 0.017.
* Pleochroism: Typically moderate to strong: Red: definite; dark red, light red, Green: strong; dark green, yellow-green, Brown: definite; dark brown, light brown, Blue: strong; dark blue, light blue.
* Ultraviolet fluorescence: Pink stones; inert to very weak red to violet in long and short wave.
* Absorption: Strong narrow band at 498 nm, and almost complete absorption of red down to 640 nm in blue and green stones; red and pink stones show lines at 458 and 451 nm as well as a broad band in the green spectrum.
* Specific gravity: 3.06+0.20−0.06.
* Density: 2.82–3.32.
The term "tourmaline" is derived from the Sinhalese "tōramalli", which refers to the carnelian gemstones.
Tourmaline was sometimes called the "Ceylonese Sri Lankan Magnet" because it could attract and then repel hot ashes due to its pyroelectric properties.
Tourmalines were used by chemists to polarize light by shining rays onto a cut and polished surface of the gem.

## Tusionites

Tusionite has the formula Mn$^{2+}$ Sn$^{4+}$ [BO $_3$] $_2$.

## Wurtzite BN

Only small amounts of the wurtzite form of boron nitride (w-BN) exist in nature as a mineral.