Iron(II) sulfate

<h2 id="uses">Uses</h2>
Industrially, ferrous sulfate is mainly used as a precursor to other iron compounds. It is a <a href="/facts/Reducing_agent/CtfSGVXC">reducing agent</a>, and as such is useful for the reduction of <a href="/facts/Chromate_ion/6xkFLIJw">chromate</a> in <a href="/facts/Cement/VfDMkk12">cement</a> to less toxic Cr(III) compounds. Historically ferrous sulfate was used in the textile industry for centuries as a <a href="/facts/Dye_fixative/KGkRrkba">dye fixative</a>. It is used historically to blacken leather and as a constituent of <a href="/facts/Iron_gall_ink/sgoK2jKM">iron gall ink</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a> The preparation of <a href="/facts/Sulfuric_acid/Wom6fymJ">sulfuric acid</a> ('oil of vitriol') by the distillation of green vitriol (iron(II) sulfate) has been known for at least 700 years.

<h3>Medical use</h3>
Main article: <a href="/facts/Iron_supplement/okvPXPWP">Iron supplement</a>
<h3>Plant growth</h3>
Iron(II) sulfate is sold as ferrous sulfate, a soil amendment<a class="footnote-ref" id="fnref:6" href="#fn:6">6</a> for lowering the pH of a high alkaline soil so that plants can access the soil's nutrients.<a class="footnote-ref" id="fnref:7" href="#fn:7">7</a>
In <a href="/facts/Horticulture/m8qBLuT3">horticulture</a> it is used for treating iron <a href="/facts/Chlorosis/bgKaKIVb">chlorosis</a>.<a class="footnote-ref" id="fnref:8" href="#fn:8">8</a> Although not as rapid-acting as <a href="/facts/Ferric_EDTA/h1CaD8aS">ferric EDTA</a>, its effects are longer-lasting. It can be mixed with compost and dug into the soil to create a store which can last for years.<a class="footnote-ref" id="fnref:9" href="#fn:9">9</a> Ferrous sulfate can be used as a <a href="/facts/Lawn/8j5Yf84C">lawn</a> conditioner.<a class="footnote-ref" id="fnref:10" href="#fn:10">10</a> It can also be used to eliminate <a href="/facts/Bryum_argenteum/mvVeSj85">silvery thread moss</a> in golf course putting greens.<a class="footnote-ref" id="fnref:11" href="#fn:11">11</a>

<h3>Pigment and craft</h3>
Ferrous sulfate can be used to stain concrete and some limestones and sandstones a yellowish rust color.<a class="footnote-ref" id="fnref:12" href="#fn:12">12</a>
<a href="/facts/Woodworker/JSttCtkP">Woodworkers</a> use ferrous sulfate solutions to color <a href="/facts/Maple/xCgQIY4z">maple</a> wood a silvery hue.
Green vitriol is also a useful reagent in the identification of mushrooms.<a class="footnote-ref" id="fnref:13" href="#fn:13">13</a>

<h3>Historical uses</h3>
Ferrous sulfate was used in the manufacture of <a href="/facts/Ink/Y7Wj0YQS">inks</a>, most notably <a href="/facts/Iron_gall_ink/sgoK2jKM">iron gall ink</a>, which was used from the <a href="/facts/Middle_Ages/RqzEKB9v">Middle Ages</a> until the end of the 18th century. Chemical tests made on the <a href="/facts/Lachish_letters/eV62cy2r">Lachish letters</a> (c. 588–586 BCE) showed the possible presence of iron.<a class="footnote-ref" id="fnref:14" href="#fn:14">14</a> It is thought that oak galls and copperas may have been used in making the ink on those letters.<a class="footnote-ref" id="fnref:15" href="#fn:15">15</a> It also finds use in <a href="/facts/Wool/AENKRTYl">wool</a> <a href="/facts/Dye/a1NSlcsG">dyeing</a> as a <a href="/facts/Mordant/KGkRrkba">mordant</a>. <a href="/facts/Harewood_(material)/9mXtlBer">Harewood</a>, a material used in <a href="/facts/Marquetry/NVJgwdaA">marquetry</a> and <a href="/facts/Parquetry/lB8hFQTJ">parquetry</a> since the 17th century, is also made using ferrous sulfate.
Two different methods for the direct application of <a href="/facts/Indigo_dye/aqC7umcC">indigo dye</a> were developed in England in the 18th century and remained in use well into the 19th century. One of these, known as china blue, involved iron(II) sulfate. After printing an insoluble form of indigo onto the fabric, the indigo was reduced to leuco-indigo in a sequence of baths of ferrous sulfate (with reoxidation to indigo in air between immersions). The china blue process could make sharp designs, but it could not produce the dark hues of other methods.
In the second half of the 1850s ferrous sulfate was used as a photographic developer for <a href="/facts/Collodion_process/7nexn45a">collodion process</a> images.<a class="footnote-ref" id="fnref:16" href="#fn:16">16</a>

<h2 id="hydrates">Hydrates</h2>
Iron(II) sulfate can be found in various states of <a href="/facts/Hydrate/dev82l69">hydration</a>, and several of these forms exist in nature or were created synthetically.

<ul><li>FeSO4·H2O (mineral: <a href="/facts/Szomolnokite/285JBNlW">szomolnokite</a>,<a class="footnote-ref" id="fnref:17" href="#fn:17">17</a> relatively rare, <a href="/facts/Monoclinic_crystal_system/5PCwXvzX">monoclinic</a><a class="footnote-ref" id="fnref:18" href="#fn:18">18</a>)</li>
<li>FeSO4·H2O (synthetic compound stable at pressures exceeding 6.2 GPa, <a href="/facts/Triclinic_crystal_system/Y6yEdqfN">triclinic</a><a class="footnote-ref" id="fnref:19" href="#fn:19">19</a>)</li>
<li>FeSO4·4H2O (mineral: <a href="/facts/Rozenite/JgCGDqLm">rozenite</a>,<a class="footnote-ref" id="fnref:20" href="#fn:20">20</a><a class="footnote-ref" id="fnref:21" href="#fn:21">21</a> white, relatively common, may be dehydration product of melanterite, monoclinic<a class="footnote-ref" id="fnref:22" href="#fn:22">22</a>)</li>
<li>FeSO4·5H2O (mineral: <a href="/facts/Siderotil/4pA1puzL">siderotil</a>,<a class="footnote-ref" id="fnref:23" href="#fn:23">23</a><a class="footnote-ref" id="fnref:24" href="#fn:24">24</a> relatively rare, triclinic<a class="footnote-ref" id="fnref:25" href="#fn:25">25</a>)</li>
<li>FeSO4·6H2O (mineral: ferrohexahydrite,<a class="footnote-ref" id="fnref:26" href="#fn:26">26</a><a class="footnote-ref" id="fnref:27" href="#fn:27">27</a> very rare, monoclinic<a class="footnote-ref" id="fnref:28" href="#fn:28">28</a>)</li>
<li>FeSO4·7H2O (mineral: <a href="/facts/Melanterite/yctgyEDV">melanterite</a>,<a class="footnote-ref" id="fnref:29" href="#fn:29">29</a><a class="footnote-ref" id="fnref:30" href="#fn:30">30</a> blue-green, relatively common, monoclinic<a class="footnote-ref" id="fnref:31" href="#fn:31">31</a>)</li></ul>

The tetrahydrate is stabilized when the temperature of aqueous solutions reaches 56.6 °C (133.9 °F). At 64.8 °C (148.6 °F) these solutions form both the tetrahydrate and monohydrate.<a class="footnote-ref" id="fnref:32" href="#fn:32">32</a>
Mineral forms are found in oxidation zones of iron-bearing ore beds, e.g. <a href="/facts/Pyrite/41CYREyr">pyrite</a>, <a href="/facts/Marcasite/vP4CW3QC">marcasite</a>, <a href="/facts/Chalcopyrite/MXBDffGw">chalcopyrite</a>, etc. They are also found in related environments, like coal fire sites. Many rapidly dehydrate and sometimes oxidize. Numerous other, more complex (either basic, hydrated, and/or containing additional cations) Fe(II)-bearing sulfates exist in such environments, with <a href="/facts/Copiapite/C7Bq09Gg">copiapite</a> being a common example.<a class="footnote-ref" id="fnref:33" href="#fn:33">33</a>

<h2 id="production-and-reactions">Production and reactions</h2>
In the finishing of <a href="/facts/Steel/aN6qWo4H">steel</a> prior to plating or coating, the steel sheet or rod is passed through <a href="/facts/Pickling_(metal)/nnhPycNe">pickling baths</a> of sulfuric acid. This treatment produces large quantities of iron(II) sulfate as a by-product.<a class="footnote-ref" id="fnref:34" href="#fn:34">34</a>

Fe + H2SO4 → FeSO4 + H2
Another source of large amounts results from the production of <a href="/facts/Titanium_dioxide/T0KWmKcz">titanium dioxide</a> from <a href="/facts/Ilmenite/fh2eXgpo">ilmenite</a> via the sulfate process.
Ferrous sulfate is also prepared commercially by oxidation of <a href="/facts/Pyrite/41CYREyr">pyrite</a>:<a class="footnote-ref" id="fnref:35" href="#fn:35">35</a>

2 FeS2 + 7 O2 + 2 H2O → 2 FeSO4 + 2 H2SO4
It can be produced by displacement of metals less reactive than <a href="/facts/Iron/QK1JYy8E">Iron</a> from solutions of their sulfate:

CuSO4 + Fe → FeSO4 + Cu
<h3>Reactions</h3>

Upon dissolving in water, ferrous sulfates form the <a href="/facts/Metal_aquo_complex/eKudHVQy">metal aquo complex</a> [Fe(H2O)6]2+, which is an almost colorless, <a href="/facts/Paramagnetic/vj1SMbbp">paramagnetic</a> ion.
On heating, iron(II) sulfate first loses its <a href="/facts/Water_of_crystallization/sbaKJNJX">water of crystallization</a> and the original green crystals are converted into a white <a href="/facts/Anhydrous/A7B0fDLE">anhydrous</a> solid. When further heated, the anhydrous material <a href="/facts/Chemical_decomposition/4X3oxvhb">decomposes</a> into <a href="/facts/Sulfur_dioxide/jDK1fIDs">sulfur dioxide</a> and <a href="/facts/Sulfur_trioxide/Ijvm08Lq">sulfur trioxide</a>, leaving a reddish-brown <a href="/facts/Iron(III)_oxide/vam0XoC5">iron(III) oxide</a>. <a href="/facts/Thermal_decomposition/Qqx9RqkW">Thermolysis</a> of iron(II) sulfate begins at about 680 °C (1,256 °F).

2 FeSO4 Δ→ Fe2O3 + SO2 + SO3
Like other iron(II) salts, iron(II) sulfate is a reducing agent. For example, it reduces <a href="/facts/Nitric_acid/UDbwGp6s">nitric acid</a> to <a href="/facts/Nitrogen_monoxide/UvhdvDzp">nitrogen monoxide</a> and <a href="/facts/Chlorine/y27UwYBM">chlorine</a> to <a href="/facts/Chloride/m9NUaUDR">chloride</a>:

6 FeSO4 + 3 H2SO4 + 2 HNO3 → 3 Fe2(SO4)3 + 4 H2O + 2 NO
6 FeSO4 + 3 Cl2 → 2 Fe2(SO4)3 + 2 FeCl3
Its mild reducing power is of value in organic synthesis.<a class="footnote-ref" id="fnref:36" href="#fn:36">36</a> It is used as the iron catalyst component of <a href="/facts/Fenton%2527s_reagent/gTBzVprG">Fenton's reagent</a>.
Ferrous sulfate can be detected by the <a href="/facts/Cerimetry/Au8fVmzv">cerimetric</a> method, which is the official method of the <a href="/facts/Indian_Pharmacopoeia_Commission/J5o6P2sE">Indian Pharmacopoeia.</a> This method includes the use of ferroin solution showing a red to light green colour change during titration.<a class="footnote-ref" id="fnref:37" href="#fn:37">37</a>

<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Iron_supplement/okvPXPWP">Iron supplement</a></li>
<li><a href="/facts/Iron(III)_sulfate/FCJ0r4j3">Iron(III) sulfate</a> (ferric sulfate), the other common simple sulfate of iron</li>
<li><a href="/facts/Copper(II)_sulfate/Ya6fPoQe">Copper(II) sulfate</a></li>
<li><a href="/facts/Ammonium_iron(II)_sulfate/QH1q2lvb">Ammonium iron(II) sulfate</a>, also known as Mohr's salt, the common double salt of ammonium sulfate with iron(II) sulfate</li>
<li><a href="/facts/Chalcanthum/rGyFVolS">Chalcanthum</a></li>
<li><a href="/facts/Ephraim_Seehl/bBKPXnhD">Ephraim Seehl</a>, known as an early manufacturer of iron(II) sulfate, which he called 'green vitriol'<a class="footnote-ref" id="fnref:38" href="#fn:38">38</a></li></ul>

<h2 id="external-links">External links</h2>

Wikimedia Commons has media related to Iron(II) sulfate.

<ul><li><a href="http://www.chemicalland21.com/industrialchem/inorganic/FERROUS%20SULFATE%20HEPTAHYDRATE.htm">"Product Information"</a>. Chemical Land21. 10 January 2007.</li>
<li><a href="/facts/T._Sterry_Hunt/cQqB85tU">Hunt TS</a> (1879). <a href="https://en.wikisource.org/wiki/The_American_Cyclop%C3%A6dia_(1879)/Copperas">"Copperas" </a>. <a href="/facts/The_American_Cyclop%25C3%25A6dia/szBM6Gxy">The American Cyclopædia</a>.</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1">Brown, Lesley (1993). The New shorter Oxford English dictionary on historical principles. Oxford [Eng.]: Clarendon. ISBN 0-19-861271-0. <a href="0-19-861271-0" target="_blank">0-19-861271-0</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
<li id="fn:2">World Health Organization (2023). The selection and use of essential medicines 2023: web annex A: World Health Organization model list of essential medicines: 23rd list (2023). Geneva: World Health Organization. hdl:10665/371090. WHO/MHP/HPS/EML/2023.02. <a href="/wiki/World_Health_Organization" target="_blank">/wiki/World_Health_Organization</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></li>
<li id="fn:3">"The Top 300 of 2022". ClinCalc. Archived from the original on 30 August 2024. Retrieved 30 August 2024. <a href="https://clincalc.com/DrugStats/Top300Drugs.aspx" target="_blank">https://clincalc.com/DrugStats/Top300Drugs.aspx</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></li>
<li id="fn:4">"Ferrous Sulfate Drug Usage Statistics, United States, 2013 - 2022". ClinCalc. Retrieved 30 August 2024. <a href="https://clincalc.com/DrugStats/Drugs/FerrousSulfate" target="_blank">https://clincalc.com/DrugStats/Drugs/FerrousSulfate</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></li>
<li id="fn:5">British Archaeology magazine. http://www.archaeologyuk.org/ba/ba66/feat2.shtml (archive) <a href="http://www.archaeologyuk.org/ba/ba66/feat2.shtml" target="_blank">http://www.archaeologyuk.org/ba/ba66/feat2.shtml</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></li>
<li id="fn:6">"Why Use Ferrous Sulfate for Lawns?". Retrieved 14 April 2018. <a href="http://homeguides.sfgate.com/use-ferrous-sulfate-lawns-83484.html" target="_blank">http://homeguides.sfgate.com/use-ferrous-sulfate-lawns-83484.html</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">"Acid or alkaline soil: Modifying pH - Sunset Magazine". www.sunset.com. 3 September 2004. Retrieved 14 April 2018. <a href="https://www.sunset.com/garden/garden-basics/acid-alkaline-soil-modifying-ph" target="_blank">https://www.sunset.com/garden/garden-basics/acid-alkaline-soil-modifying-ph</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
<li id="fn:8">Koenig, Rich and Kuhns, Mike: Control of Iron Chlorosis in Ornamental and Crop Plants. (Utah State University, Salt Lake City, August 1996) p.3 <a href="/wiki/Utah_State_University" target="_blank">/wiki/Utah_State_University</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></li>
<li id="fn:9">Handreck K (2002). Gardening Down Under: A Guide to Healthier Soils and Plants (2nd ed.). Collingwood, Victoria: CSIRO Publishing. pp. 146–47. ISBN 0-643-06677-2. <a href="0-643-06677-2" target="_blank">0-643-06677-2</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></li>
<li id="fn:10">Handreck K (2002). Gardening Down Under: A Guide to Healthier Soils and Plants (2nd ed.). Collingwood, Victoria: CSIRO Publishing. pp. 146–47. ISBN 0-643-06677-2. <a href="0-643-06677-2" target="_blank">0-643-06677-2</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></li>
<li id="fn:11">Controlling moss in putting greens by Cook, Tom; McDonald, Brian; and Merrifield, Kathy. <a href="https://www.gcsaa.org/docs/default-source/research-and-information/weeds/controlling-moss-in-putting-greens.pdf#page=2/" target="_blank">https://www.gcsaa.org/docs/default-source/research-and-information/weeds/controlling-moss-in-putting-greens.pdf#page=2/</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></li>
<li id="fn:12">How To Stain Concrete with Iron Sulfate <a href="http://www.stainedfloor.com/Iron_Recipes.html" target="_blank">http://www.stainedfloor.com/Iron_Recipes.html</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></li>
<li id="fn:13">Svrček M (1975). A color guide to familiar mushrooms (2nd ed.). London: Octopus Books. p. 30. ISBN 0-7064-0448-3. <a href="0-7064-0448-3" target="_blank">0-7064-0448-3</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></li>
<li id="fn:14">Torczyner, Lachish Letters, pp. 188–95 <a href="#fnref:14" class="footnote-back-ref">↩</a></li>
<li id="fn:15">Hyatt, The Interpreter's Bible, 1951, volume V, p. 1067 <a href="#fnref:15" class="footnote-back-ref">↩</a></li>
<li id="fn:16">Brothers A (1892). Photography: its history, processes. London: Griffin. p. 257. OCLC 558063884. <a href="https://archive.org/details/b24886853" target="_blank">https://archive.org/details/b24886853</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></li>
<li id="fn:17">Ralph J, Chautitle I. "Szomolnokite". Mindat.org. Retrieved 3 August 2014. <a href="http://www.mindat.org/min-3859.html" target="_blank">http://www.mindat.org/min-3859.html</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></li>
<li id="fn:18">Meusburger J (September 2019). "Transformation mechanism of the pressure-induced C2/c-to-P transition in ferrous sulfate monohydrate single crystals". Journal of Solid State Chemistry. 277: 240–252. doi:10.1016/j.jssc.2019.06.004. S2CID 197070809. <a href="https://www.sciencedirect.com/science/article/abs/pii/S0022459619302853" target="_blank">https://www.sciencedirect.com/science/article/abs/pii/S0022459619302853</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></li>
<li id="fn:19">Meusburger J (September 2019). "Transformation mechanism of the pressure-induced C2/c-to-P transition in ferrous sulfate monohydrate single crystals". Journal of Solid State Chemistry. 277: 240–252. doi:10.1016/j.jssc.2019.06.004. S2CID 197070809. <a href="https://www.sciencedirect.com/science/article/abs/pii/S0022459619302853" target="_blank">https://www.sciencedirect.com/science/article/abs/pii/S0022459619302853</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></li>
<li id="fn:20">"Rozenite Mineral Data". Retrieved 3 August 2014. <a href="http://www.webmineral.com/data/Rozenite.shtml" target="_blank">http://www.webmineral.com/data/Rozenite.shtml</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></li>
<li id="fn:21">"Rozenite". <a href="https://www.mindat.org/min-3469.html" target="_blank">https://www.mindat.org/min-3469.html</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></li>
<li id="fn:22">Meusburger J (September 2022). "Low-temperature crystallography and vibrational properties of rozenite (FeSO4·4H2O), a candidate mineral component of the polyhydrated sulfate deposits on Mars" (PDF). <a href="http://www.minsocam.org/msa/ammin/AM_Preprints/8502ForbesPreprint.pdf" target="_blank">http://www.minsocam.org/msa/ammin/AM_Preprints/8502ForbesPreprint.pdf</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></li>
<li id="fn:23">"Siderotil Mineral Data". Retrieved 3 August 2014. <a href="http://www.webmineral.com/data/Siderotil.shtml" target="_blank">http://www.webmineral.com/data/Siderotil.shtml</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></li>
<li id="fn:24">"Siderotil". <a href="https://www.mindat.org/min-3643.html" target="_blank">https://www.mindat.org/min-3643.html</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></li>
<li id="fn:25">Jambor JL, Nordstrom DK, Alpers CN (2000). "Metal-sulfate Salts from Sulfide Mineral Oxidation". Reviews in Mineralogy and Geochemistry. 40 (1): 303–350. Bibcode:2000RvMG...40..303J. doi:10.2138/rmg.2000.40.6. Retrieved 18 November 2022. <a href="https://pubs.geoscienceworld.org/msa/rimg/article-abstract/40/1/303/140666/Metal-sulfate-Salts-from-Sulfide-Mineral-Oxidation?redirectedFrom=fulltext" target="_blank">https://pubs.geoscienceworld.org/msa/rimg/article-abstract/40/1/303/140666/Metal-sulfate-Salts-from-Sulfide-Mineral-Oxidation?redirectedFrom=fulltext</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></li>
<li id="fn:26">"Ferrohexahydrite Mineral Data". Retrieved 3 August 2014. <a href="http://www.webmineral.com/data/Ferrohexahydrite.shtml" target="_blank">http://www.webmineral.com/data/Ferrohexahydrite.shtml</a> <a href="#fnref:26" class="footnote-back-ref">↩</a></li>
<li id="fn:27">"Ferrohexahydrite". <a href="https://www.mindat.org/min-1517.html" target="_blank">https://www.mindat.org/min-1517.html</a> <a href="#fnref:27" class="footnote-back-ref">↩</a></li>
<li id="fn:28">Jambor JL, Nordstrom DK, Alpers CN (2000). "Metal-sulfate Salts from Sulfide Mineral Oxidation". Reviews in Mineralogy and Geochemistry. 40 (1): 303–350. Bibcode:2000RvMG...40..303J. doi:10.2138/rmg.2000.40.6. Retrieved 18 November 2022. <a href="https://pubs.geoscienceworld.org/msa/rimg/article-abstract/40/1/303/140666/Metal-sulfate-Salts-from-Sulfide-Mineral-Oxidation?redirectedFrom=fulltext" target="_blank">https://pubs.geoscienceworld.org/msa/rimg/article-abstract/40/1/303/140666/Metal-sulfate-Salts-from-Sulfide-Mineral-Oxidation?redirectedFrom=fulltext</a> <a href="#fnref:28" class="footnote-back-ref">↩</a></li>
<li id="fn:29">"Melanterite Mineral Data". Retrieved 3 August 2014. <a href="http://www.webmineral.com/data/Melanterite.shtml" target="_blank">http://www.webmineral.com/data/Melanterite.shtml</a> <a href="#fnref:29" class="footnote-back-ref">↩</a></li>
<li id="fn:30">"Melanterite". <a href="https://www.mindat.org/min-2633.html" target="_blank">https://www.mindat.org/min-2633.html</a> <a href="#fnref:30" class="footnote-back-ref">↩</a></li>
<li id="fn:31">Peterson RC (2003). "THE RELATIONSHIP BETWEEN Cu CONTENT AND DISTORTION IN THE ATOMIC STRUCTURE OF MELANTERITE FROM THE RICHMOND MINE, IRON MOUNTAIN, CALIFORNIA" (PDF). <a href="https://rruff.info/doclib/cm/vol41/CM41_937.pdf" target="_blank">https://rruff.info/doclib/cm/vol41/CM41_937.pdf</a> <a href="#fnref:31" class="footnote-back-ref">↩</a></li>
<li id="fn:32">Seidell A, Linke WF (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). New York: D. Van Nostrand Company. p. 343. <a href="https://archive.org/details/solubilitiesino01seidgoog" target="_blank">https://archive.org/details/solubilitiesino01seidgoog</a> <a href="#fnref:32" class="footnote-back-ref">↩</a></li>
<li id="fn:33">"Copiapite". <a href="https://www.mindat.org/min-1124.html" target="_blank">https://www.mindat.org/min-1124.html</a> <a href="#fnref:33" class="footnote-back-ref">↩</a></li>
<li id="fn:34">Wildermuth E, Stark H, Friedrich G, Ebenhöch FL, Kühborth B, Silver J, et al. "Iron Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. ISBN 978-3-527-30673-2. <a href="978-3-527-30673-2" target="_blank">978-3-527-30673-2</a> <a href="#fnref:34" class="footnote-back-ref">↩</a></li>
<li id="fn:35">Lowson RT (1982). "Aqueous oxidation of pyrite by molecular oxygen". Chem. Rev. 82 (5): 461–497. doi:10.1021/cr00051a001. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:35" class="footnote-back-ref">↩</a></li>
<li id="fn:36">Lee Irvin Smith, J. W. Opie (1948). "o-Aminobenzaldehyde". Org. Synth. 28: 11. doi:10.15227/orgsyn.028.0011. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:36" class="footnote-back-ref">↩</a></li>
<li id="fn:37">Al-Obaidi AH. "ASSAY OF FERROUS SULPHATE" (PDF). Archived from the original (PDF) on 29 September 2023. <a href="https://web.archive.org/web/20230929051907/https://cpha.tu.edu.iq/images/%D8%B9%D9%85%D8%B1_%D8%AD%D8%B3%D9%8A%D9%86/ASSAY_OF_FERROUS_SULPHATE__ali_hussein-%D9%85%D8%AD%D9%88%D9%84_1.pdf" target="_blank">https://web.archive.org/web/20230929051907/https://cpha.tu.edu.iq/images/%D8%B9%D9%85%D8%B1_%D8%AD%D8%B3%D9%8A%D9%86/ASSAY_OF_FERROUS_SULPHATE__ali_hussein-%D9%85%D8%AD%D9%88%D9%84_1.pdf</a> <a href="#fnref:37" class="footnote-back-ref">↩</a></li>
<li id="fn:38">Pryce W (1778). Mineralogia Cornubiensis; a Treatise on Minerals, Mines and Mining. London: Phillips. p. 33. <a href="https://archive.org/details/b30449170" target="_blank">https://archive.org/details/b30449170</a> <a href="#fnref:38" class="footnote-back-ref">↩</a></li>
</ol>

Iron(II) sulfate open-in-new

Iron(II) sulfate