A collector's guide to Kopasz Hill andesite quarry, Hungary: its geology, mining history and notable minerals, illustrated with the 93 specimens documented from this locality on EarthWonders.
Key facts
Kopasz Hill andesite quarry is one of the modern classic European localities for hyalite, the colourless, glass-clear opal variety that collectors value for its wet lustre, rounded âdew dropâ surfaces, and startling ultraviolet response. The specimens come from cavities, fractures, and narrow mineralized zones in a Miocene volcanic body of the TokajâZemplĂ©n volcanic region of northeastern Hungary, where pyroxene-andesite and related intermediate volcanic rocks were quarried on an industrial scale for aggregate and building stone. What makes the locality special is not a broad mineral diversity in the manner of an ore mine, but a very particular late-stage cavity assemblage: hyalite opal on dark andesite, commonly with aragonite or calcite beneath it, plus subordinate silica, carbonate, clay, sulphate, and iron minerals.
The best Kopasz Hill pieces have a look that is instantly recognizable. Transparent, botryoidal to droplet-like hyalite sits on black to dark-grey andesite as if water had beaded and frozen in place. Some specimens are simply clear hyalite over matrix; others show ghostly carbonates beneath the opal skin, including aragonite sprays and calcite forms. Under shortwave ultraviolet light the hyalite can glow an electric green; where carbonate is involved, the fluorescence can become more complex, with yellow, white, or pale bluish responses depending on the substrate and replacement textures. This combination of clarity, sculptural botryoidal form, dark contrast, and fluorescence is the reason specimens from this quarry moved quickly from local collecting interest into the international fine-mineral market after the celebrated 2013 finds.
Regional View
Country View
Historically, the quarry belongs to the long stone-working landscape of Tokaj-Hegyalja, a wine region where volcanic rock, vineyards, cellars, and villages are intimately mixed. Large-scale quarrying began in the early twentieth century, with crushing and transport infrastructure built to feed Hungaryâs demand for road and construction aggregate. For mineral collectors, however, the pivotal moment was far later: a narrow hyalite-rich zone opened in the working quarry in 2013. The exposure was small, reported at only about 10â15 metres long, but it yielded specimens whose quality changed the reputation of the locality almost overnight. Since collecting has not been permitted since summer 2015, and blasting damaged many pieces before they ever reached collectors, undamaged specimens from the 2013â2015 period now carry the localityâs real premium.
Search for specimens: View all specimens from Kopasz Hill andesite quarry, Hungary
Kopasz Hill andesite quarry is recorded in mineralogical sources under several closely related locality names, including Kopasz-hegy, the TĂĄllya andesite quarry, and the Tarcal quarry operation. The quarry is placed in the Tokaj District of Borsod-AbaĂșj-ZemplĂ©n County, in the ZemplĂ©n Mountains, also historically called the Tokaj Mountains. The working lies in the Kopasz HillâFekete Hill area and has been operated in connection with Colas ĂszakkĆ Ltd.; the Colas Tarcal mine page identifies the commercial rock material as pyroxene-dacite, andesite, and permitted mixtures involving inert construction-demolition material for aggregate products. As of the operatorâs July 6, 2026 notice, the Tarcal mine operation was closed indefinitely for technical reasons, a commercial-status note rather than a collecting invitation.
Geologically, the quarry exposes a Miocene, Sarmatian-age subvolcanic intermediate volcanic body associated with the EperjesâTokaj/ZemplĂ©n volcanic belt. The industrial geology literature treats the Kopasz Hill rock as a subvolcanic pyroxene-andesite body emplaced among rhyolitic tuff and tuffite units; other descriptions emphasize olivine-bearing pyroxene andesite, columnar jointing, and local pyroxene-dacitic varieties. A University of Miskolc field-trip guide places the main volcanic construction at roughly 12â13 million years ago and notes a later magmatic intrusion about 9 million years ago visible in the mine walls, while other Hungarian geological sources describe the worked body as around 11.7 million years old. For collectors, the practical point is that cooling, fracturing, vesiculation, and later fluid movement created the cavities and seams in which silica, carbonates, sulphides, clays, sulphates, and iron oxides were deposited.
This is not an ore locality in the classic mining sense. The economically worked material is crushed stone, not metal ore, and the collectible minerals are late cavity and fracture fillings in andesite. The celebrated hyalite zone is described as an andesite interval impregnated with hyalite over only about 10â15 metres. Within and around such openings, the paragenesis appears to be a low-temperature, late-stage volcanic/hydrothermal and lateral-secretion assemblage: carbonates such as calcite, aragonite, dolomite, and siderite formed in cavities and fractures; silica followed as opal, hyalite, chalcedony, quartzine, and quartz; and clay minerals, sulphates, pyriteâmarcasite, iron oxides, and baryte represent additional late alteration and weathering products. The finest collector pieces are not large crystals in open vugs, but coatings and replacements whose aesthetic depends on texture, transparency, contrast, and the survival of fragile opal surfaces.
The mining history reaches back to Baron György MajlĂĄth, who is credited with opening an early quarry in 1861 after pyroxene-andesite was recognized in the southern part of Kopasz Hill. Industrial-scale working developed in the late 1920s: sources describe large-scale operation from 1927, the opening of the quarry by UrikĂĄny-Zsilvölgyi Magyar KĆszĂ©nbĂĄnya Rt. on land leased through TĂĄllyai KĆbĂĄnya Rt. in 1928, and full large-scale extraction beginning in 1929. That same year brought the first crusher and a cableway to the railway loading area. By the 1930s the quarry had become one of Hungaryâs important crushed-stone operations. After nationalisation in 1949 it continued through several operating structures; in 1991 the North Hungarian Mining Company was privatized by the French Colas group, leading to the Colas ĂszakkĆ name. A major investment in 2008 added new crushing and screening capacity.
Collecting access is the limiting fact of the locality. The quarry is an industrial site where explosives are used, and published locality notes state plainly that collecting has not been permitted since summer 2015. This matters for both safety and specimen supply. Many pieces were broken by blasting or heavy equipment before they could be trimmed; even undamaged-looking specimens may show bruised opal beads, sheared matrix edges, or repaired contact points if they were recovered from shot rock. Any modern claim of fresh self-collection should be treated cautiously unless accompanied by permission from the operator and clear provenance.
The important specimen finds are concentrated around the 2013 hyalite discovery. Collectors and dealers recognize a core suite of water-clear botryoidal opal, opal on aragonite, and opal over calcite from the 2013â2015 collecting window. Documented specimens include thumbnails and miniatures only a few centimetres across, small-cabinet pieces with calcite visible beneath hyalite, and rarer cabinet plates where transparent hyalite coats broad andesite surfaces. The localityâs fame rests on those select, visually clean examples: dark matrix, transparent rounded opal, intact droplet surfaces, and strong fluorescence.
Opal from Kopasz Hill is overwhelmingly collected as hyalite, especially opal-AN forming clear, colourless to slightly milky botryoidal, bubbly, droplet-like, stalactitic, and crustiform coatings on dark andesite; older and broader records also note milk opal and black opal varieties from the locality. The most desirable pieces came from the 2013 hyalite-rich zone, where transparent opal coated cavity walls and in places overgrew calcite or aragonite, creating layered specimens that fluoresce vividly under ultraviolet light. Documented pieces range from thumbnail aggregates around 1â2 cm through 5â10 cm miniatures and small cabinets, with exceptional larger plates recorded in recent photo documentation; quality is judged by water clarity, high vitreous lustre, undamaged rounded âdew dropâ surfaces, strong green shortwave fluorescence, sharp contrast against dark andesite, and interesting carbonate forms visible beneath the opal rather than by size alone.
Aragonite from Kopasz Hill is a supporting but important collector species because it is one of the carbonate substrates that gives the localityâs hyalite specimens their layered, sculptural character. It is reported as white to faintly pink, needle-radiating and botryoidal aggregates in andesite cavities, commonly partly or completely covered by later transparent hyalite; good examples show recognizable aragonite texture under a glassy opal skin rather than a shapeless white mass. Stand-alone aragonite specimens are much less common and less market-defining than opal, but aragonite-in-hyalite combinations are among the most distinctive Kopasz Hill pieces, especially when the white carbonate adds daylight contrast and an additional fluorescent response beneath the green-glowing hyalite.
Other documented minerals from Kopasz Hill include apatite, baryte, calcite, dolomite, epsomite, goethite, gypsum, halloysite, hematite, hexahydrite, jarosite, marcasite, montmorillonite, nontronite, pickeringite, pyrite, quartz, chalcedony, quartzine, siderite, and sphĂ€rosiderite. Older Tokaj collector literature for the Kopasz-hegy quarries also records millimetric milk-white or colourless tabular tridymite in vesicles of the Miocene andesite, although modern labelled specimen suites are dominated by hyalite rather than tridymite. The locality is not known as a type locality for a mineral species; its rarities are instead paragenetic and textural, especially sulphate efflorescences, clay minerals, pyriteâmarcasite occurrences, siderite/sphĂ€rosiderite, and hyalite replacements or coatings after carbonate forms.
Kopasz Hill hyalite is one of those localities where condition is the first authenticity test. The quarry was worked by blasting, and the finest opal occurs as a thin, rounded coating on hard andesite. Broken bubbles, bruised high points, cleaved-off skins, and fresh-looking sawn or trimmed matrix edges are common. A specimen can be genuine and still heavily damaged; an unusually pristine piece should show consistent lustre across the opal surface, no suspicious resin gloss in fractures, and no mismatch between the broken matrix and the opal crust.
The main labelling issue is not usually outright fakery but locality looseness. Labels may say Kopasz Hill, Kopasz-hegy, Tarcal, TĂĄllya, Tokaj, ZemplĂ©n Mountains, or simply Hungary. These names can refer to the same collecting tradition, but serious collectors should preserve the most specific original label available, especially if it mentions Kopasz Hill andesite quarry, Tarcal, Borsod-AbaĂșj-ZemplĂ©n County. Be careful with labels that simply say âTokaj hyalite,â because the TokajâZemplĂ©n volcanic region has several opal and silica occurrences.
Documented market specimens are natural hyalite on andesite; dyed or synthetic opal is not a known defining problem for the locality. Still, the materialâs âwet glassâ appearance makes glue, oil, resin, or water-wetted sales photography worth watching for. Check high-magnification surfaces for filled cracks, artificial gloss in damaged zones, and repaired contacts between opal crust and matrix. Hyalite itself should not show play-of-colour like precious opal; its attraction here is transparency, botryoidal form, and fluorescence.
Fluorescence is central to the appeal. The hyalite is best tested with shortwave UV, where good specimens can glow bright green. Longwave response may be weaker or more yellowish-green, and carbonate-bearing specimens can show yellow, white, bluish, or afterglow effects from calcite or aragonite beneath or beside the opal. Because fluorescent hyalite commonly owes its response to trace uranyl species, specimens should be handled as normal mineral specimens: do not grind, cut, lick, or inhale dust; wash hands after handling; and avoid long-term storage in damp environments that might encourage sulphate efflorescences on associated minerals.
Rarity is now controlled by access and condition. Small pieces and damaged examples still appear with some regularity, and thumbnail to miniature hyalite specimens are available on the international market. Clean small-cabinet pieces with strong fluorescence are appreciably scarcer. Large, undamaged plates with continuous transparent hyalite, dark matrix contrast, and aragonite or calcite association are genuinely difficult to replace, especially because collecting was stopped after the initial productive period. Current market offerings show everything from inexpensive educational chips and small 2â3 cm pieces to several-hundred-dollar miniatures and four-figure cabinet specimens when clarity, aesthetics, and provenance align.
In the nineteenth-century landscape drawings of TĂĄllya, Kopasz Hill still had a shape that no collector today can visit intact. The 1867 Tokaj-Hegyalja album shows the village from across the Szerencs stream valley: behind the then-truncated tower of the Catholic church stands DorgĂł Hill, and behind the Reformed church rises the double height of Kopasz Hill. Modern quarrying has erased that old double summit. The change is a useful reminder that this locality is not a quiet abandoned prospect discovered by hobbyists, but a working industrial mountain whose rock helped build the surrounding region.
The industrial age arrived with infrastructure as dramatic as the quarry face itself. Large-scale extraction began at the end of the 1920s, and in 1929 the operation gained both a crusher and a cableway linked to a railway loading area. Later maps showed quarry yards on the northwest side of Kopasz Hill and on both western and eastern sides of DorgĂł, with the cableway and industrial railway drawn as part of the working landscape. The crusher building, photographed on a 1930s postcard and again in ruins in 2013, survived as a kind of industrial fossil: not a mineral specimen, but a relic of the machinery that made the specimensâ survival so accidental.
The hyalite story was short, bright, and unforgiving. In 2013 a narrow zone only about 10â15 metres long produced the transparent opal that made Kopasz Hill famous among collectors. The best pieces looked improbable: colourless, rounded opal droplets on dark andesite, sometimes draped over hidden aragonite or calcite. Then came the two constraints that define the locality today. First, the quarry worked by blasting, so many specimens were shattered or bruised before anyone could trim them. Second, by summer 2015 collecting was no longer permitted. A classic Kopasz Hill specimen is therefore often a survival from a very small window of time and space: a few metres of rock, a couple of collecting seasons, and a great deal of luck.
One of the quarryâs stranger geological episodes came not from opal but from something that looked like coal. During a 2014 visit to the sinking level of the TĂĄllya/Kopasz Hill andesite open pit, geologists examined two visible andesite types and a black, coal-like footwall material exposed along the eastern to southeastern side of the level. The glossy black rock could easily mislead an eye trained on mining, but petrographic work identified it not as an exploitable coal seam, but as a contact-altered andesite tuffite containing thin lignitic streaks and cut by small apophyses of the andesite body. The conclusion mattered industrially as well as scientifically: despite the coal-like appearance, the setting did not indicate a workable lignite or coal body.
The quarry also occupies an unusually sensitive cultural setting. The Tokaj Wine Region Historic Cultural Landscape became a UNESCO World Heritage site in 2002, and the quarry area lies within that landscape. In 2012 Tokaj-Hegyalja was designated Hungaryâs first protected historic landscape under national cultural-heritage law. That makes Kopasz Hill a locality where mineral collecting, aggregate production, vineyards, tourism, village views, and landscape rehabilitation all overlap. The waste-rock dumps visible from TĂĄllya were once regular conical forms that dominated the settlementâs view; later rehabilitation reshaped and integrated them. Few fluorescent-opal localities have such a strong double identity: prized cabinet specimens on one side, and a World Heritage wine landscape on the other.
Mindat: Kopasz Hill andesite quarry, Tarcal, Tokaj District, Borsod-AbaĂșj-ZemplĂ©n County, Hungary â Core modern locality record, coordinates, alternate names, mineral list, access warning, and the key 2013 hyalite-zone summary.
Society of Economic Geologists Student Chapter, University of Miskolc. âIndustrial Minerals in the NE Part of Hungary â Short Course,â TelkibĂĄnya, November 5â8, 2018 â Field-trip guide with the TĂĄllya andesite quarry history, geology, production figures, and operating context.
MĂłdosnĂ© Bugyi IldikĂł and Csima PĂ©ter. âA tĂĄllyai andezitbĂĄnya szerepe a tĂĄjkĂ©pben Ă©s a tĂĄjszerkezetben / The Role of TĂĄllyaâs Andesite Quarry in the Landscape and Landscape Pattern,â 4D 76, 64â75, 2025 â Detailed account of the quarryâs landscape setting, World Heritage context, mining history, crusher, cableway, waste dumps, and rehabilitation.
Minerofil: âĂsvĂĄnygyƱjtĆ kalauz 1. Tokaji-hegysĂ©gâ â Hungarian collecting guide for the Tokaj Mountains, including TĂĄllya/Kopasz-hegy andesite-quarry minerals.
MAMIT: âA magyarorszĂĄgi ĂĄsvĂĄnyfajokâ â Hungarian mineral-species reference that records historical opal/hyalite occurrences in the TokajâZemplĂ©n region, including TĂĄllya/Kopasz-hegy.
Zelenka Tibor and KertĂ©sz Botond. âTĂĄllya andezitbĂĄnya sĂŒllyesztĆi szintjĂ©n elĆfordulĂł andezittĂpusok kĆzettani Ă©s ĂĄsvĂĄnytani jellemzĂ©seâ â Petrographic and mineralogical treatment of andesite types exposed at the TĂĄllya quarry sinking level, including the coal-like contact-altered tuffite.
Tokody, L. âMineralien des Kopaszhegy bei TĂĄllya im Tokajer Gebirge,â 1964 â Historical mineralogical work repeatedly cited in Hungarian locality literature for Kopasz-hegy/TĂĄllya.
Koller et al. âSensationeller Neufund von Hyalit im Tokajer Gebirge,â Mineralien-Welt 2018/2, 14â23 â Specialist article on the sensational new hyalite find in the Tokaj Mountains, cited in later Hungarian mineral-species supplements for the Tarcal/Kopasz Hill material.
Attila Jakab Mindat photo gallery â Public specimen-photo records documenting Kopasz Hill opal-AN/hyalite, including aragonite and calcite associations, dimensions, and condition notes from the 2015 upload suite.
Mindat locality page: Kopasz Hill andesite quarry â Best single external starting point for the mineral list, alternate names, locality coordinates, and collecting-status warning.
Colas ĂszakkĆ: Tarcal bĂĄnyaĂŒzem â Current operator page for the Tarcal mine operation, products, contacts, and operating notice.
University of Miskolc SEG short-course guide â Concise English-language industrial-geology description of the TĂĄllya andesite quarry.
4D article on the TĂĄllya andesite quarry landscape â Best source for the quarryâs cultural-landscape setting, historic infrastructure, and rehabilitation context.
Minerofil Tokaj Mountains collecting guide â Useful Hungarian-language mineral-collecting guide to the wider Tokaj volcanic region.
Tiszazugi Földrajzi MĂșzeum: Andezit from TĂĄllya, Kopasz-hegy â Museum-style explanation of the Kopasz-hegy andesite, its Miocene volcanic setting, and physical appearance.
Minfind: Kopasz Hill hyalite and aragonite specimen record â Archived dealer record showing the international market treatment of Kopasz Hill hyalite-aragonite combinations.
Minfind: Arkenstone Kopasz Hill hyalite specimen record â High-end market example documenting a small but expensive water-clear hyalite specimen from the locality.
SZ MinĂ©raux opal listings â Dealer listings showing continued European market availability of Kopasz Hill hyalite specimens across several price levels.
Studio Mineralia Kopasz Hill hyalite listing â Retail specimen description noting shortwave fluorescence and the 2013â2015 appearance window.
