{"title":"Mass Mine (Shaft C)","description":"\u003ch2\u003eMass City, Ontonagon County, Michigan, USA\u003c\/h2\u003e\n\u003cp\u003eThe historic Mass Mine of Ontonagon County, Michigan was a significant producer of copper for many decades. Some time after production stopped, some mineral collectors ventured down into the abandoned shafts to recover the fine specimens that remained below the surface. These specimens were collected in the early 1970s from the Mass C shaft at the third level, from an area they called the \"Silver Forest.\"\u003c\/p\u003e","products":[{"product_id":"quartz-adularia-and-epidote-on-amygdaloidal-basalt","title":"Quartz, Microcline, and Epidote on Amygdaloidal Basalt","description":"\u003cp\u003eA beautiful mineral combination of milky quartz with a vitreous luster, light orange microcline variety adularia, and granular green epidote. The crystals sit in a little pocket with an amygdaloidal basalt matrix. It is from the historic Mass C mine in Ontonagon, Michigan. I a quired this piece from Karl Schaffer who collected it in the early 70s when he and his friends were granted access to old mine shafts on private property, venturing up to half a mile underground. These shafts are now inaccessible, and very few specimens from this locality exist on the market today. \u003c\/p\u003e","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":51464577614097,"sku":"Cu29","price":45.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/il_fullxfull.6811903483_4scp.jpg?v=1745523712"},{"product_id":"adularia","title":"Microcline Var. Adularia","description":"\u003cp\u003eA stunning thumbnail specimen of the microcline variety, adularia, from the historic Mass C Mine in Ontonagon, Michigan. I acquired this piece from the miner, Karl Schaffer, who collected it in the early 70s when he and his friends were granted access to old mine shafts on private property, venturing up to half a mile underground. This specimen was discovered in the 3rd level of the mine shaft, which was coined the \"Silver Forest.\" \u003c\/p\u003e\n\u003cp\u003eThe unique and vibrant orange color of the microcline is due to the presence of disseminated copper within the crystals. This thumbnail-sized specimen shows particularly good color and luster.\u003c\/p\u003e","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":51464579678481,"sku":"Cu34","price":25.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/il_fullxfull.6763861602_jirw.jpg?v=1768939859"},{"product_id":"cu30","title":"Quartz, Microcline, and Epidote","description":"\u003cp\u003eA beautiful milky quartz specimen lightly encrusted with distinctive orange microcline crystals, accented by bright green epidote and perched atop dark amygdaloidal basalt. This lovely piece comes from the historic Mass C shaft in Ontonagon, Michigan. I acquired this specimen from Karl Schaffer, who collected it in the early 70s when he and his friends were exploring old mine shafts—venturing up to half a mile underground. These shafts are now inaccessible, and very few of these specimens are available on the market. The orange coloration of the microcline is due to disseminated copper, offering a notable contrast against the quartz and epidote. A unique and tangible piece of Michigan's rich mining history. \u003c\/p\u003e","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":51727747973393,"sku":"Cu30","price":40.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/Cu30_3_31566176-0e11-41c5-b507-4039976c4a2f.jpg?v=1750374416"},{"product_id":"native-copper-microcline-var-adularia-epidote-quartz-and-tenorite","title":"Native Copper, Microcline (Var. Adularia), Epidote, Quartz, and Tenorite","description":"\u003cp\u003eExcellent native copper matrix specimen with tenorite-coated copper accented by crystals of green epidote, orange microcline variety adularia, and milky to clear quartz. This combination of minerals makes for an intriguing and visually interesting piece with great contrast. An awesome piece of history from Michigan's Keweenaw peninsula. \u003c\/p\u003e\n\u003cp\u003eI acquired this specimen from Karl Schaffer, who collected it in the early 70s when he and his friends were exploring the Mass Mine shafts. This piece was discovered on the 3rd level of the Mass C shaft, from the area coined the \"Silver Forest.\" These shafts are now inaccessible, and very few of these specimens are available on the market.\u003c\/p\u003e","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53044496498961,"sku":"Cu03","price":65.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/il_fullxfull.6264296411_8f63.jpg?v=1768940693"},{"product_id":"quartz-epidote-and-microcline-var-adularia","title":"Quartz, Epidote, and Microcline Var. Adularia","description":"\u003cp\u003eA remarkable quartz, microcline variety adularia, and epidote thumbnail specimen from the historic Mass C shaft in Ontonagon, Michigan. I acquired this piece from Karl Schaffer who collected it in the early 70s when he and his friends were exploring the now inaccessible Mass Mine. The piece features peach-colored microcline crystals, colored by disseminated copper, strikingly contrasted against milky quartz and green epidote. A unique and hard to come by piece of Michigan's rich mining history.\u003cbr\u003e\u003c\/p\u003e","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53045180104977,"sku":"Cu33","price":20.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/il_1588xN.6763735968_m429.webp?v=1768949290"},{"product_id":"native-copper-adularia-epidote-and-tenorite","title":"Native Copper, Adularia, Epidote, and Tenorite","description":"\u003cp\u003e\u003cspan\u003eA stunning specimen from the Mass Mine featuring intricate copper crystallization with a tenorite-coating, interwoven between crystals of green epidote and orange microcline of the variety adularia. \u003c\/span\u003e\u003cbr\u003e\u003cbr\u003e\u003cspan\u003eI acquired this specimen from Karl Schaffer, who collected it in the early 70s when he and his friends were exploring the Mass Mine shafts. This piece was discovered on the 3rd level of the Mass C shaft, from the area coined the \"Silver Forest.\" These shafts are now inaccessible, and very few of these specimens are available on the market.\u003c\/span\u003e\u003c\/p\u003e","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53045355413777,"sku":"Cu04","price":42.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/il_fullxfull.6264254725_ca3z_1.jpg?v=1768953923"},{"product_id":"cu06","title":"Microcline Var. Adularia, Epidote, and Tenorite-Coated Copper","description":"\u003cp\u003eAwesome specimen featuring native copper with black tenorite coating and peach-orange crystals of adularia on a matrix with epidote and quartz. A great multi-mineral specimen from Michigan's Keweenaw Peninsula, one of the United States most iconic copper localities.\u003c\/p\u003e","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53045827272977,"sku":"Cu06","price":75.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/il_fullxfull.6264680783_dc55.webp?v=1768964022"},{"product_id":"min3060-microcline-var-adularia-copper-quartz-and-epidote","title":"Microcline var. Adularia, Copper, Quartz  and Epidote","description":"An excellent specimen from Michigan's historic copper country that dates back to the early 1970's when it was collected from an abandoned mine shaft. It features lustrous microcline crystals, of the adularian variety, with a peachy-orange coloration due to the presence of disseminated copper within the crystal. Small bits of native copper poke out from below the surface, with a black tenorite coating. Granular epidote with bright green hues adds excellent contrast to the orange adularia. ","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53049995002129,"sku":"min3060","price":60.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/min3060.png?v=1769068127"},{"product_id":"min3064native-copper-quartz-and-epidote","title":"Native Copper, Quartz, and Epidote","description":"Beautiful native copper specimen, collected from the Mass C Mine \"Silver Forest\" on the 3rd level, showcasing an intricate formation of copper perched at the peak of its green-hued matrix. The matrix contains small crystals of quartz and epidote, and it sits up nicely for display. The copper is oxidized with a tenorite coating, with some copper peaking out from below the surface lower on the specimen. \n\nI acquired this specimen from Karl Schaffer, who collected it in the early 70s when he and his friends were exploring the Mass Mine shafts. This piece was discovered on the 3rd level of the Mass C shaft, from the area coined the \"Silver Forest.\" These shafts are now inaccessible, and very few of these specimens are available on the market.","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53051316797713,"sku":"min3064","price":50.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/min3064_bb0b4635-f225-4a2a-9f83-925abdc2b429.png?v=1769566744"},{"product_id":"min3140microcline-var-adularia-and-native-copper","title":"Microcline Var. Adularia and Native Copper","description":"An attractive combination specimen featuring strong color contrast and well-formed crystals. Lustrous microcline of the adularia variety occurs in warm orange crystals perched atop earthy green epidote, with native copper visible between and beneath the microcline. The copper displays a brown-black tarnish that adds depth and contrast to the overall composition. Collected in the early 1970s from a now permanently inaccessible locality.","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53381164990737,"sku":"min3140","price":40.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/min3140_2_of_5.jpg?v=1775540562"},{"product_id":"min3128-dupduplicate-sku-and-quartz","title":"Native Copper and Quartz","description":"A sculptural specimen of native copper in association with quartz and epidote from the Mass Mine, Shaft C, Ontonagon County, Michigan, collected in the early 1970s from the third level of the mine. The copper is the defining feature, having formed as casts around quartz crystals that are no longer present, producing sharp, angular copper forms that faithfully retain the geometry of the original crystals. Where quartz persists, the copper can be seen conforming closely along crystal faces, reflecting the intimate spatial relationship between the two phases during formation. The quartz is clear to white with a blocky habit, offering a bright contrast to the warm reddish-brown tones of the copper, while small patches of green epidote distributed across the specimen contribute additional color to the assemblage. This specimen was acquired directly from the collector who retrieved it — a Michigan Tech geology student at the time, who accessed the third level of the shaft with a small group before the entrance was permanently sealed with concrete. Material from this specific occurrence is unlikely to ever be recovered again, making this an appealing acquisition for those with an interest in historically significant specimens from uncommon Michigan localities.","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53381530091793,"sku":"min3128 (DUP)","price":50.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/min3128_1_of_6.jpg?v=1775541336"},{"product_id":"min3131microcline-var-adularia","title":"Microcline Var. Adularia","description":"Collected in the early 1970s from the third level of the Mass Mine, Shaft C, Ontonagon County, Michigan, this specimen of adularia (a variety of microcline) represents uncommon material from a locality unlikely to yield new specimens. The adularia crystals display a strong luster and a distinctive warm orange coloration, the result of disseminated copper present within the crystals themselves. A well-crystallized and mineralogically noteworthy thumbnail for collectors with an interest in feldspar varieties or the classic copper-bearing assemblages of Michigan's Upper Peninsula.","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53381530222865,"sku":"min3131","price":48.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/min3131_1_of_4.jpg?v=1775535438"},{"product_id":"min3141microcline-quartz-epidote","title":"Microcline, Quartz, \u0026 Epidote","description":"Beautiful green epidote with small patched of clear quartz, accented by orange microcline of the adularia variety. Collected in the early 1970s from a now permanently inaccessible locality. A lovely little specimen with high contrast and glittery appearance.","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53456721936657,"sku":"min3141","price":20.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/min3141_1_of_6.jpg?v=1775535435"},{"product_id":"min3154quartz-prehnite-and-native-copper","title":"Quartz, Prehnite, and Native Copper","description":"Elongated milky quartz crystals extending from pale green prehnite on basalt matrix. Small flecks of tarnished native copper are visible just above the prehnite surface in several locations. The matrix displays granular green epidote forming a distinct boundary between the basalt and prehnite along one edge of the specimen. A nice assemblage representing the classic mineral association found in Michigan's Keweenaw copper deposits.","brand":"Adamantine Minerals","offers":[{"title":"Default Title","offer_id":53475670720785,"sku":"min3154","price":18.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/files\/min3154_5.jpg?v=1777424224"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0900\/2277\/3009\/collections\/karl_s_minerals_8_d27560fc-36d6-4bff-98dd-cbcd63c8e0d4.jpg?v=1778054116","url":"https:\/\/adamantineminerals.com\/collections\/mass-c-mine-keweenaw-mineral-specimens.oembed","provider":"Adamantine Minerals","version":"1.0","type":"link"}