Hellyerite

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title: "Hellyerite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["nickel-minerals", "carbonate-minerals", "monoclinic-minerals", "minerals-in-space-group-15"] description: "Carbonate mineral" topic_path: "general/nickel-minerals" source: "https://en.wikipedia.org/wiki/Hellyerite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Carbonate mineral ::

::data[format=table title="infobox mineral"]

Field	Value
name	Hellyerite
image	Hellyerite-Heazlewoodite-Zaratite-255032.jpg
imagesize	260px
caption	Zaratite (emerald-green coating), hellyerite (powder-blue) and heazlewoodite (light bronze)
category	Carbonate mineral
formula	NiCO3·5.5(H2O)
IMAsymbol	Hy
strunz	5.CA.20
system	Monoclinic
class	Prismatic (2/m)
(same H-M symbol)
symmetry	C2/c
unit cell	a = 10.77, b = 7.29
c = 18.68 [Å]; β = 94°: Z = 8
color	Pale blue
habit	As crystal fragments and microcrystalline coatings
twinning	Fine lamellar parallel to cleavage
cleavage	One perfect, two good at 112° to each other and perpendicular to the perfect cleavage
mohs	2.5
luster	Vitreous
diaphaneity	Semitransparent
gravity	1.97
opticalprop	Biaxial (−)
refractive	nα = 1.455 nβ = 1.503 nγ = 1.549
birefringence	δ = 0.094
pleochroism	X = Y = very pale greenish blue; Z = pale greenish blue
2V	Measured: 85°
alteration	Decomposes on air exposure
references
::

| name = Hellyerite | image = Hellyerite-Heazlewoodite-Zaratite-255032.jpg | imagesize = 260px | alt = | caption = Zaratite (emerald-green coating), hellyerite (powder-blue) and heazlewoodite (light bronze) | category = Carbonate mineral | formula = NiCO3·5.5(H2O) | IMAsymbol = Hy | molweight = | strunz = 5.CA.20 | dana = | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = C2/c | unit cell = a = 10.77, b = 7.29 c = 18.68 [Å]; β = 94°: Z = 8 | color = Pale blue | colour = | habit = As crystal fragments and microcrystalline coatings | twinning = Fine lamellar parallel to cleavage | cleavage = One perfect, two good at 112° to each other and perpendicular to the perfect cleavage | fracture = | tenacity = | mohs = 2.5 | luster = Vitreous | streak = | diaphaneity = Semitransparent | gravity = 1.97 | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.455 nβ = 1.503 nγ = 1.549 | birefringence = δ = 0.094 | pleochroism = X = Y = very pale greenish blue; Z = pale greenish blue | 2V = Measured: 85° | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = Decomposes on air exposure | other = | prop1 = | prop1text = | references = Hellyerite, NiCO3·6(H2O), is a hydrated nickel carbonate mineral. It is light blue to bright green in colour, has a hardness of 2.5, a vitreous luster, a white streak and crystallises in the monoclinic system. The crystal habit is as platy and mammillary encrustations on its matrix. It is a pentahydrate according to X-ray crystallography. The solid consists of [Ni2(CO3)2(H2O)8] subunits with an extra pair of water of hydration.

Occurrence

The environment of formation, associated only with metamorphosed ultramafic rocks, is diagnostic compared with gaspeite, another nickel carbonate which is associated with supergene weathering of nickel sulfides.

Hellyerite is observed forming in shear planes in serpentinite, produced by carbonation of the serpentinite. Hellyerite forms in this environment in nickel rich serpentinites, which are metamorphosed equivalents of ultramafic cumulate rocks such as peridotite and dunite. Peridotite and dunite, when fresh, can contain up to ~4,000 ppm nickel within olivine.

It was first identified in 1958 in the Old Lord Brassy mine, Tasmania, Australia and named after Henry Hellyer (1791–1832), Chief Surveyor of the Van Diemens Land Company. It is also reported from the Pafuri nickel deposit in Limpopo Province, South Africa.

References

References

1. Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
2. [http://webmineral.com/data/Hellyerite.shtml Hellyerite at Webmineral.com]
3. [http://rruff.geo.arizona.edu/doclib/hom/hellyerite.pdf Handbook of Mineralogy]
4. [http://www.mindat.org/min-1853.html Mindat.org]
5. (2016). "Crystal Structure and Hydrate Water Content of Synthetic Hellyerite, NiCO₃·5.5H₂O". Zeitschrift für Anorganische und Allgemeine Chemie.
6. Williams KL,Threadgold IM,Hounslow AW. Hellyerite: A new nickel carbonate from Heazlewoord, Tasmania. ''The American Mineralogist'',1959;44:533–538. [http://www.minsocam.org/ammin/AM44/AM44_533.pdf]

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