# Hendricksite

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> Source: https://en.wikipedia.org/wiki/Hendricksite
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{{Short description|Mineral in the trioctahedral mica group}}
{{Infobox mineral
| boxtextcolor  = black
| boxbgcolor    = #7e5b3d
| name          = Hendricksite
| category = [Phyllosilicate](/source/Phyllosilicate) minerals
| group = [Mica](/source/Mica) group, trioctahedral mica group
| formula       = KZn<sub>3</sub>(Si<sub>3</sub>Al)O<sub>10</sub>(OH)<sub>2</sub>
| IMAsymbol     = Hds<ref>{{Cite journal | last = Warr | first = L.N. | date = 2021 | title = IMA–CNMNC approved mineral symbols | journal = Mineralogical Magazine | volume = 85 | issue = 3 | pages = 291–320 | doi = 10.1180/mgm.2021.43 | bibcode = 2021MinM...85..291W | s2cid = 235729616 | doi-access = free}}</ref>
| strunz        = 09.EC.20
| system        = [Monoclinic](/source/Monoclinic)
| dana          = 71.2.2b.6
| class         = Prismatic (2/m)
| symmetry      = ''B2''/m
| unit cell     = 499.58
| molweight     = 493.25
| color         = Copper-, bronze brown, dark reddish brown to reddish black
| cleavage      = Perfect on {001}
| mohs          = 2.5 – 3
| opticalprop   = Biaxial (−)
| refractive    = n<sub>α</sub> = 1.598 – 1.624 <br/>n<sub>β</sub> = 1.658 – 1.686 <br/>n<sub>γ</sub> = 1.660 – 1.697
| birefringence = 0.062 – 0.073
| pleochroism   = X = Pale yellow, <br/>Y = Z = Light chestnut brown
| 2V            = Measured: 2°- 8° <br/>Calculated: 20°- 44°
| dispersion    = Slight <br/>r < v
| fluorescence  = None
| streak        = Red brown
| gravity       = 2.86 - 3.43
| diaphaneity   = Translucent
| impurities    = Ti, Fe, Ca, Ba, Li, Na, F
}}
'''Hendricksite''' is a member of the trioctahedral [mica](/source/mica)s group. The mineral was named by Clifford Frondel and Jun Ito in honor of [Sterling Brown Hendricks](/source/Sterling_B._Hendricks), who studied micas. It was approved in 1966 by the [IMA](/source/International_Mineralogical_Association).<ref name=":0">{{Cite web|title=Hendricksite|url=https://www.mindat.org/min-1864.html|access-date=2021-02-11|website=www.mindat.org}}</ref>

== Physical properties ==
Hendricksite can either form short prismatic crystals,<ref name=":1">{{Cite web |last=Minerals |first=Dakota Matrix |title=Hendricksite mineral information and data |url=https://www.dakotamatrix.com/mineralpedia/5796/hendricksite |access-date=2022-12-16 |website=www.dakotamatrix.com |language=en}}</ref> or foliated ones that are platy and seem two dimensional. It occurs in clusters,<ref name=":2" /> and these aggregates have interlocking crystals. These crystals are more commonly [anhedral](/source/Euhedral_and_anhedral) – a crystal with no faces, but rarely they can be [euhedral](/source/euhedral) – crystals with well defined surfaces. The anhedral crystals can grow up to 30&nbsp;cm, and are commonly deformed, while the euhedral crystals can reach 14 cms in size of mechanical deformation.<ref name=":0" /> It has [pleochroic](/source/Pleochroism) attributes, which is an optical phenomenon that makes minerals to be seen a different color depending on the axis it is inspected on. On the X axis, it can be seen in a pale brown color, while on the Y and Z axis it is seen in a light chestnut brown color.<ref name=":2">{{Cite web|title=Hendricksite Mineral Data|url=http://webmineral.com/data/Hendricksite.shtml|access-date=2021-02-11|website=webmineral.com}}</ref> It doesn't show any fluorescence under either shortwave, or longwave [ultraviolet light](/source/ultraviolet_light).<ref name=":3">{{Cite web |title=FOMS – Hendricksite – Franklin Mineral Information |url=https://www.fomsnj.org/mineral.aspx?minid=266&minName=Hendricksite |access-date=2022-12-16 |website=www.fomsnj.org}}</ref>

== Chemical properties ==
It mostly consists of oxygen (38.92%), zinc (18.56%), silicon (15.37%) and manganese (10.02%), but otherwise contains potassium (7.13%), aluminium (7.11%), magnesium (2.46%) and a negligible amount of hydrogen (0.41%). It has a barely detectable, 1% radioactivity measured by GRapi (Gamma Ray [American Petroleum Institute](/source/American_Petroleum_Institute) Units) due to its potassium content, which gives the mineral its radioactive attributes.<ref name=":2" /> Zinc in hendricksite's formula can be replaced with manganese(II) or magnesium. Currently, this is the only mica known for its zinc dominancy, and it is the zinc analogue of [phlogopite](/source/phlogopite), [annite](/source/annite), and [shirozulite](/source/shirozulite). It can have calcium, iron, titanium, barium, lithium, natrium and fluorine impurities. It has three known [polytypes](/source/polytypes), which include 1M, 2M<sub>1</sub>, and 3A.<ref name=":0" /> Hendricksite can be included in a solid solution series with zincohendricksite and manganoanhendricksite being the endmembers, a solid solution series meaning the three sharing a general formula but having a substitution of elements in at least one of the atomic sites.<ref name=":1" /> A part of the solid solutions series might be magnesium bearing hendricksite, the series perhaps being complete to [phlogopite](/source/phlogopite) and partially to [biotite](/source/biotite).<ref name=":3" /> In the case of trioctahedral micas, the ellipsoids of the cationic sites have an uniaxial positive optical property, elongated to ''c''. However, in hendricksite's case this is only typical for the two zinc-free sides. In the octahedras containing zinc, the ellipsoids are uniaxial negative and flattened to ''a''.<ref>{{Cite journal |last1=Robert |first1=J. -L. |last2=Gaspérin |first2=M. |date=1985-03-01 |title=Crystal structure refinement of hendricksite, A Zn- and Mn-rich trioctahedral potassium mica: A contribution to the crystal chemistry of zinc-bearing minerals |url=https://doi.org/10.1007/BF01082453 |journal=Tschermaks mineralogische und petrographische Mitteilungen |language=en |volume=34 |issue=1 |pages=1–14 |doi=10.1007/BF01082453 |bibcode=1985TMPM...34....1R |issn=1438-1168|url-access=subscription }}</ref>

== Occurrences and localities ==
It can appear only in metamorphosed stratiform zinc deposits, in irregular lens or sheet like skarn bodies. It can be found in the Franklin mine in New Jersey, US.<ref name=":0" /> The mineral can be found at the Sterling hill as well, although it is much rarer due to the higher iron and magnesium concentrations. It occurs with [vesuvianite](/source/vesuvianite), [bustamite](/source/bustamite) and [feldspars](/source/feldspars),<ref name=":3" /> additional associated minerals being minerals of the [axinite](/source/axinite) group, [calcite](/source/calcite), [rhodonite](/source/rhodonite), [willemite](/source/willemite), [hancockite](/source/hancockite), as well as [andrasite](/source/andrasite).<ref name=":0" />

== References ==
{{Reflist}}
<references group="" responsive="0"></references>

{{Phyllosilicates}}

Category:Zinc minerals
Category:Minerals described in 1966
Category:Trioctahedral mica group

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Adapted from the Wikipedia article [Hendricksite](https://en.wikipedia.org/wiki/Hendricksite) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Hendricksite?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.