{"id":21310,"date":"2024-03-24T18:41:44","date_gmt":"2024-03-24T18:41:44","guid":{"rendered":"https:\/\/rockseeker.com\/?p=21310"},"modified":"2024-03-28T01:21:11","modified_gmt":"2024-03-28T01:21:11","slug":"franklinite","status":"publish","type":"post","link":"https:\/\/rockseeker.com\/franklinite\/","title":{"rendered":"Spinel\u2019s Strange Cousin: A Guide to Franklinite"},"content":{"rendered":"

Franklinite may not catch the eye at first glance, but it holds a unique intrigue due to its composition. This mineral, known for its deep black crystals<\/a>, is exceptionally rare and can only be found in one specific location on the planet. Although its outward appearance may seem ordinary, franklinite captivates scientists and mineral enthusiasts with its distinctive scientific qualities and formation.<\/p>\n\n\n\n

So, let\u2019s take a closer look at franklinite and talk briefly about where it\u2019s found and how to avoid fakes.<\/p>\n\n\n\n

What is Frankilinite?<\/h2>\n\n\n
\n
\"\"
credit: Breck P. Kent\/Shutterstock.com<\/figcaption><\/figure><\/div>\n\n\n

Franklinite is a relative of spinels, and by extension magnetite<\/a>. It\u2019s made up of zinc, iron, and oxygen. It\u2019s a relatively hard mineral, sitting between 5.5 and 6.0 on the Moh\u2019s scale<\/a> and is generally found as black or grey crystals in combination with calcite, willemite, and zinc.<\/p>\n\n\n\n

The mineral itself has a slightly variable composition. It includes both ferric and ferrous oxide, with their differing electrical values. These can be replaced by manganese to some extent in the crystal\u2019s formation, with trivalent manganese taking the place of ferrous oxide.<\/p>\n\n\n\n

Franklinite is most often spread throughout the host rock as tiny crystals, just grains in the bedrock. The samples that most people are after are the occasional large, euhedral crystals found in the area but these are quite rare. Below I\u2019ll talk about some of the measures counterfeiters have used to replicate this rare mineral, but there\u2019s more to it than just collecting.<\/p>\n\n\n\n

The State Mineral of New Jersey<\/h2>\n\n\n
\n
\"\"
image: @NJGov\/x.com<\/a><\/figcaption><\/figure><\/div>\n\n
\n
\"\"
image: Stan Celestian<\/a><\/figcaption><\/figure><\/div>\n\n\n

Since franklinite is only found in one spot in New Jersey to any appreciable degree, it\u2019s become the state mineral.<\/p>\n\n\n\n

Franklinite was discovered in Franklin, New Jersey in 1819. The Franklin Mine<\/a>, where it was originally found, was primarily aimed for zinc ore. It and its sister mine in nearby Ogdensburg have produced nearly 350 distinct mineral species between them. Notably, many of these are fluorescent materials.<\/p>\n\n\n\n

Today the mine is long gone, and Franklin is no longer a mining town. The 1,200 foot mine is now covered in water since operations have ceased, but it was an important contribution to the economy of New Jersey\u2019s early history.<\/p>\n\n\n\n

Not bad for what started as a relatively simple mining operation for magnetite.<\/p>\n\n\n\n

A Relative of Spinel<\/h2>\n\n\n
\n
\"\"
Franklinite is a close relative of spinel.<\/figcaption><\/figure><\/div>\n\n\n

Spinel gemstones are some of the coolest in the world. Spinel are mainly known for their red and blue varieties, which are comparable in color to precious gemstones such as ruby and sapphire. There\u2019s even a color-changing variety, that will appear in different shades depending on the local lighting.<\/p>\n\n\n\n

While spinel is often very hard and used as a gemstone, franklinite is a much softer mineral and unlikely to be mistaken for spinel but the chemical relation is quite fascinating.<\/p>\n\n\n\n

Like most spinels, franklinite is considered a solid solution. That means that it will have varying quantities of different metals throughout it\u2019s crystalline structure, although if it gets too far from the ideal it really should be considered something else entirely.<\/p>\n\n\n\n

Where is Franklinite Found?<\/h2>\n\n\n
\n
\"\"
image: Stan Celestian<\/a><\/figcaption><\/figure><\/div>\n\n\n

Franklinite is only found in New Jersey. Specifically, it\u2019s named after the town of Franklin in that state. It is occasionally found elsewhere, but not in the desirable large crystalline form. Instead, it\u2019s found very rarely and generally interspersed with rocks.<\/p>\n\n\n\n

In the area where the type locality comes from, however, it\u2019s a fairly common mineral.<\/p>\n\n\n\n

Unfortunately, if you\u2019re planning on hunting some down for yourself you may be out of luck. While older mining operations often found the large, desirable crystals these are considered mined out for the most part at this point.<\/p>\n\n\n\n

So you may have to resort to buying it from someone, which introduces its own set of complications.<\/p>\n\n\n\n

Buyer Beware: Counterfeit Franklinite<\/h2>\n\n\n\n

Desirable minerals are often faked, it\u2019s just a consequence of the market. Because of the single type-locality and the fact that larger crystals aren\u2019t found any longer, there are some issues with buying it.<\/p>\n\n\n\n

The first is simply enhanced crystals. These have had all sorts of janky methods used to clean the surface and hide cracks. Franklinite often cracks in larger formations, reducing the value of the sample.<\/p>\n\n\n\n

So why not fill it in with boot polish?<\/p>\n\n\n\n

I mean, I personally wouldn\u2019t, but it\u2019s a testament to the kind of odd things people will do to increase the value of a crystal. Boot polish was an old method, and once the volatile components are gone it can be hard to detect without damaging the crystal further.<\/p>\n\n\n\n

Crude methods like this are a hallmark of older mineral specimen fakes.<\/p>\n\n\n\n

The other problem is that some people would assemble smaller pieces into one large crystal and then clean them up. These fakes can be harder to detect.<\/p>\n\n\n\n

And then you have some people who will just sell magnetite crystals as franklinite due to their similarities. Due to the variable composition of franklinite, it can be hard to tell the difference other than the surface sheen which may not be evident if the crystal is rough enough.<\/p>\n\n\n\n

Apart from carefully checking the surface and making sure it\u2019s magnetic, there aren\u2019t a lot of non-destructive tests you can perform at home. Even comparing the magnetism to a known sample of magnetite is a losing battle due to the varying zinc and iron balance in differing specimens.<\/p>\n\n\n\n

While the market does have a lot of counterfeit material, large crystals of franklinite do change hands on occasion. Just be very careful where you decide to buy them, since the market is<\/em> covered in fake material.<\/p>\n\n\n\n

It will also come at a high cost, especially if it\u2019s a real sample. I\u2019ve seen great crystals listed for just shy of $10,000 through jewelers and mineral dealers. It\u2019s worth getting a certificate from a geologist or gemologist if you\u2019re going to spend that kind of money.<\/p>","protected":false},"excerpt":{"rendered":"

Franklinite may not catch the eye at first glance, but it holds a unique intrigue due to its composition. This mineral, known for its deep black crystals, is exceptionally rare and can only be found in one specific location on the planet. Although its outward appearance may seem ordinary, franklinite captivates scientists and mineral enthusiasts […] More<\/a><\/p>\n","protected":false},"author":5,"featured_media":24817,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[30],"tags":[],"yoast_head":"\nSpinel\u2019s Strange Cousin: A Guide to Franklinite - Rock Seeker<\/title>\n<meta name=\"description\" content=\"Franklinite may not catch the eye at first glance, but it holds a unique intrigue due to its composition. This mineral, known for its deep black crystals, is exceptionally rare and can only be found in one specific location on the planet.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/rockseeker.com\/franklinite\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Spinel\u2019s Strange Cousin: A Guide to Franklinite - Rock Seeker\" \/>\n<meta property=\"og:description\" content=\"Franklinite may not catch the eye at first glance, but it holds a unique intrigue due to its composition. This mineral, known for its deep black crystals, is exceptionally rare and can only be found in one specific location on the planet.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/rockseeker.com\/franklinite\/\" \/>\n<meta property=\"og:site_name\" content=\"Rock Seeker\" \/>\n<meta property=\"article:published_time\" content=\"2024-03-24T18:41:44+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2024-03-28T01:21:11+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/rockseeker.com\/wp-content\/uploads\/2024\/03\/franklinite.png\" \/>\n\t<meta property=\"og:image:width\" content=\"1200\" \/>\n\t<meta property=\"og:image:height\" content=\"675\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"author\" content=\"Jeremy Hall\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Jeremy Hall\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"6 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/rockseeker.com\/franklinite\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/rockseeker.com\/franklinite\/\"},\"author\":{\"name\":\"Jeremy Hall\",\"@id\":\"https:\/\/rockseeker.com\/#\/schema\/person\/91f8adede9c1b3a67c809effd6a6e8ef\"},\"headline\":\"Spinel\u2019s Strange Cousin: A Guide to Franklinite\",\"datePublished\":\"2024-03-24T18:41:44+00:00\",\"dateModified\":\"2024-03-28T01:21:11+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/rockseeker.com\/franklinite\/\"},\"wordCount\":1008,\"publisher\":{\"@id\":\"https:\/\/rockseeker.com\/#organization\"},\"image\":{\"@id\":\"https:\/\/rockseeker.com\/franklinite\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/rockseeker.com\/wp-content\/uploads\/2024\/03\/franklinite.png\",\"articleSection\":[\"Rocks and Precious Stones\"],\"inLanguage\":\"en-US\",\"copyrightYear\":\"2024\",\"copyrightHolder\":{\"@id\":\"https:\/\/rockseeker.com\/#organization\"}},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/rockseeker.com\/franklinite\/\",\"url\":\"https:\/\/rockseeker.com\/franklinite\/\",\"name\":\"Spinel\u2019s Strange Cousin: A Guide to Franklinite - Rock Seeker\",\"isPartOf\":{\"@id\":\"https:\/\/rockseeker.com\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/rockseeker.com\/franklinite\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/rockseeker.com\/franklinite\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/rockseeker.com\/wp-content\/uploads\/2024\/03\/franklinite.png\",\"datePublished\":\"2024-03-24T18:41:44+00:00\",\"dateModified\":\"2024-03-28T01:21:11+00:00\",\"description\":\"Franklinite may not catch the eye at first glance, but it holds a unique intrigue due to its composition. This mineral, known for its deep black crystals, is exceptionally rare and can only be found in one specific location on the planet.\",\"breadcrumb\":{\"@id\":\"https:\/\/rockseeker.com\/franklinite\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/rockseeker.com\/franklinite\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/rockseeker.com\/franklinite\/#primaryimage\",\"url\":\"https:\/\/rockseeker.com\/wp-content\/uploads\/2024\/03\/franklinite.png\",\"contentUrl\":\"https:\/\/rockseeker.com\/wp-content\/uploads\/2024\/03\/franklinite.png\",\"width\":1200,\"height\":675},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/rockseeker.com\/franklinite\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/rockseeker.com\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Spinel\u2019s Strange Cousin: A Guide to Franklinite\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/rockseeker.com\/#website\",\"url\":\"https:\/\/rockseeker.com\/\",\"name\":\"Rock Seeker\",\"description\":\"\",\"publisher\":{\"@id\":\"https:\/\/rockseeker.com\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/rockseeker.com\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/rockseeker.com\/#organization\",\"name\":\"Rock Seeker\",\"url\":\"https:\/\/rockseeker.com\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/rockseeker.com\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/rockseeker.com\/wp-content\/uploads\/2022\/12\/wide-rock-seeker-logo-dark-800-\u00d7-80-px.png\",\"contentUrl\":\"https:\/\/rockseeker.com\/wp-content\/uploads\/2022\/12\/wide-rock-seeker-logo-dark-800-\u00d7-80-px.png\",\"width\":800,\"height\":80,\"caption\":\"Rock Seeker\"},\"image\":{\"@id\":\"https:\/\/rockseeker.com\/#\/schema\/logo\/image\/\"}},{\"@type\":\"Person\",\"@id\":\"https:\/\/rockseeker.com\/#\/schema\/person\/91f8adede9c1b3a67c809effd6a6e8ef\",\"name\":\"Jeremy Hall\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/rockseeker.com\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/1c11e585f04c46e058099f8924557975?s=96&d=mm&r=pg\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/1c11e585f04c46e058099f8924557975?s=96&d=mm&r=pg\",\"caption\":\"Jeremy Hall\"},\"description\":\"Jeremy is a professional writer, but his real passion lies with stones. With two decades of collecting behind him, as well as a decade of cutting, he loves to share his broad experience and knowledge about rockhounding. These days he can be found in his workshop, setting the stones he dreamed of as a child. You can find his knowledge here, and his handiwork at his Etsy shop.\",\"url\":\"https:\/\/rockseeker.com\/author\/jeremy-hall\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Spinel\u2019s Strange Cousin: A Guide to Franklinite - Rock Seeker","description":"Franklinite may not catch the eye at first glance, but it holds a unique intrigue due to its composition. This mineral, known for its deep black crystals, is exceptionally rare and can only be found in one specific location on the planet.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/rockseeker.com\/franklinite\/","og_locale":"en_US","og_type":"article","og_title":"Spinel\u2019s Strange Cousin: A Guide to Franklinite - Rock Seeker","og_description":"Franklinite may not catch the eye at first glance, but it holds a unique intrigue due to its composition. This mineral, known for its deep black crystals, is exceptionally rare and can only be found in one specific location on the planet.","og_url":"https:\/\/rockseeker.com\/franklinite\/","og_site_name":"Rock Seeker","article_published_time":"2024-03-24T18:41:44+00:00","article_modified_time":"2024-03-28T01:21:11+00:00","og_image":[{"width":1200,"height":675,"url":"https:\/\/rockseeker.com\/wp-content\/uploads\/2024\/03\/franklinite.png","type":"image\/png"}],"author":"Jeremy Hall","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Jeremy Hall","Est. reading time":"6 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/rockseeker.com\/franklinite\/#article","isPartOf":{"@id":"https:\/\/rockseeker.com\/franklinite\/"},"author":{"name":"Jeremy Hall","@id":"https:\/\/rockseeker.com\/#\/schema\/person\/91f8adede9c1b3a67c809effd6a6e8ef"},"headline":"Spinel\u2019s Strange Cousin: A Guide to Franklinite","datePublished":"2024-03-24T18:41:44+00:00","dateModified":"2024-03-28T01:21:11+00:00","mainEntityOfPage":{"@id":"https:\/\/rockseeker.com\/franklinite\/"},"wordCount":1008,"publisher":{"@id":"https:\/\/rockseeker.com\/#organization"},"image":{"@id":"https:\/\/rockseeker.com\/franklinite\/#primaryimage"},"thumbnailUrl":"https:\/\/rockseeker.com\/wp-content\/uploads\/2024\/03\/franklinite.png","articleSection":["Rocks and Precious Stones"],"inLanguage":"en-US","copyrightYear":"2024","copyrightHolder":{"@id":"https:\/\/rockseeker.com\/#organization"}},{"@type":"WebPage","@id":"https:\/\/rockseeker.com\/franklinite\/","url":"https:\/\/rockseeker.com\/franklinite\/","name":"Spinel\u2019s Strange Cousin: A Guide to Franklinite - Rock Seeker","isPartOf":{"@id":"https:\/\/rockseeker.com\/#website"},"primaryImageOfPage":{"@id":"https:\/\/rockseeker.com\/franklinite\/#primaryimage"},"image":{"@id":"https:\/\/rockseeker.com\/franklinite\/#primaryimage"},"thumbnailUrl":"https:\/\/rockseeker.com\/wp-content\/uploads\/2024\/03\/franklinite.png","datePublished":"2024-03-24T18:41:44+00:00","dateModified":"2024-03-28T01:21:11+00:00","description":"Franklinite may not catch the eye at first glance, but it holds a unique intrigue due to its composition. This mineral, known for its deep black crystals, is exceptionally rare and can only be found in one specific location on the planet.","breadcrumb":{"@id":"https:\/\/rockseeker.com\/franklinite\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/rockseeker.com\/franklinite\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/rockseeker.com\/franklinite\/#primaryimage","url":"https:\/\/rockseeker.com\/wp-content\/uploads\/2024\/03\/franklinite.png","contentUrl":"https:\/\/rockseeker.com\/wp-content\/uploads\/2024\/03\/franklinite.png","width":1200,"height":675},{"@type":"BreadcrumbList","@id":"https:\/\/rockseeker.com\/franklinite\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/rockseeker.com\/"},{"@type":"ListItem","position":2,"name":"Spinel\u2019s Strange Cousin: A Guide to Franklinite"}]},{"@type":"WebSite","@id":"https:\/\/rockseeker.com\/#website","url":"https:\/\/rockseeker.com\/","name":"Rock Seeker","description":"","publisher":{"@id":"https:\/\/rockseeker.com\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/rockseeker.com\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/rockseeker.com\/#organization","name":"Rock Seeker","url":"https:\/\/rockseeker.com\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/rockseeker.com\/#\/schema\/logo\/image\/","url":"https:\/\/rockseeker.com\/wp-content\/uploads\/2022\/12\/wide-rock-seeker-logo-dark-800-\u00d7-80-px.png","contentUrl":"https:\/\/rockseeker.com\/wp-content\/uploads\/2022\/12\/wide-rock-seeker-logo-dark-800-\u00d7-80-px.png","width":800,"height":80,"caption":"Rock Seeker"},"image":{"@id":"https:\/\/rockseeker.com\/#\/schema\/logo\/image\/"}},{"@type":"Person","@id":"https:\/\/rockseeker.com\/#\/schema\/person\/91f8adede9c1b3a67c809effd6a6e8ef","name":"Jeremy Hall","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/rockseeker.com\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/1c11e585f04c46e058099f8924557975?s=96&d=mm&r=pg","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/1c11e585f04c46e058099f8924557975?s=96&d=mm&r=pg","caption":"Jeremy Hall"},"description":"Jeremy is a professional writer, but his real passion lies with stones. With two decades of collecting behind him, as well as a decade of cutting, he loves to share his broad experience and knowledge about rockhounding. These days he can be found in his workshop, setting the stones he dreamed of as a child. You can find his knowledge here, and his handiwork at his Etsy shop.","url":"https:\/\/rockseeker.com\/author\/jeremy-hall\/"}]}},"wps_subtitle":"","_links":{"self":[{"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/posts\/21310"}],"collection":[{"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/comments?post=21310"}],"version-history":[{"count":7,"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/posts\/21310\/revisions"}],"predecessor-version":[{"id":24916,"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/posts\/21310\/revisions\/24916"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/media\/24817"}],"wp:attachment":[{"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/media?parent=21310"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/categories?post=21310"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rockseeker.com\/wp-json\/wp\/v2\/tags?post=21310"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}