National Limestone Quarry No. 2 at Mount Pleasant Mills has become one of the most distinctive modern American wavellite localities because its best pieces are not the familiar dark-green Arkansas balls, but luminous yellow-green to chartreuse, apple-green, pale lemon, and colorless radiating aggregates on pale sandstone. The visual effect is airy and sharply graphic: pea-like hemispheres, circular “rising sun” sprays, and botryoidal crusts scattered over tan to buff matrix, sometimes with white or colorless radial fans opening like tiny cut geodes.
Photo: Wikimedia Commons / Rob Lavinsky, iRocks.com
The locality sits on Lime Ridge near Mount Pleasant Mills in Snyder County, Pennsylvania. The operating quarry is a limestone producer, but the wavellite occurrence that collectors prize is not simply a limestone-pocket mineral. The phosphate assemblage occurs in siliciclastic rocks of the Ridgeley Member of the Old Port Formation, in a narrow zone of steeply dipping beds near the upper bench and southern property-line road. That setting gives the locality its character: wavellite grows on sandstone and in narrow fractures, fossil cavities, and small openings rather than as broad linings in carbonate vugs.
Photo: Wikimedia Commons / Rob Lavinsky, iRocks.com
Historically, the quarry had long been known to collectors for calcite, strontianite, fluorite, celestine, and Devonian fossils. Wavellite changed the reputation of the place. The “green” was noticed by quarry owner Eric Stahl around the beginning of the 2000s while work was being done along a perimeter road on the upper bench. Local collectors confirmed the species, clubs began seeking access, and the locality moved from a regional curiosity to a serious collector locality. By the 2020s, machine-assisted work and laboratory study had shown that Mount Pleasant Mills wavellite could produce large, displayable, well-colored specimens—material strong enough to stand in conversation with better-known Arkansas wavellite, but with a look and geology entirely its own.
Collectors look for intact hemispheres and sharp radial sprays, strong yellow-green or apple-green color, attractive spacing on matrix, and pieces that preserve the contrast between pale sandstone, colorless or white wavellite, and green or lemon-yellow growth. The most sophisticated pieces are not always the brightest; some show color zoning, open radial fans, fossil-hosted growth, or unusual associations with other phosphates such as cacoxenite, planerite, variscite, turquoise, and vauxite.
Search for specimens: View all wavellite specimens from National Limestone Quarry No. 2, Mount Pleasant Mills, Pennsylvania, USA
National Limestone Quarry No. 2 is the smaller of two Stahl-family National Limestone operations in the Mount Pleasant Mills–Middleburg area. It is an active limestone quarry on Lime Ridge, near Mount Pleasant Mills in Perry Township, Snyder County. Mindat records the locality as a limestone quarry with limestone as the commodity and a mineral list that includes cacoxenite, calcite, celestine, dolomite, fluorite, planerite, quartz, sphalerite, strontianite, turquoise, variscite, vauxite, and wavellite.
The quarry mines mainly the Keyser and Tonoloway formations in Lime Ridge, and the long-familiar quarry specimens—calcite, dolomite, strontianite, celestine, and fluorite—belong to that carbonate-quarry setting. The wavellite occurrence, however, is tied to the Ridgeley Member of the Old Port Formation, a Lower Devonian quartz arenite described as white, pale gray, or buff, medium-grained, slightly limonitic, and fossiliferous. The wavellite-bearing beds are steep to nearly vertical and run in a relatively narrow zone roughly parallel to the upper-bench perimeter road along the southern quarry boundary.
The phosphate mineralization is interpreted in recent field-study abstracts as a post-Alleghenian epigenetic event associated with brittle deformation and renewed tectonism of undetermined age. In practical collector terms, that means the attractive wavellite is structurally localized: it is not expected everywhere in the quarry, and productive pockets are concentrated in the upper-bench wavellite pits and related fracture zones rather than throughout the limestone operation.
Collecting access is controlled and should be treated as a privilege, not a public right. Individuals are not permitted to enter the quarry on their own. Published field-trip notes state that collecting is arranged through clubs, with safety gear, insurance, sign-in sheets, safety meetings, and owner orientation required. Club trips have commonly included the Middleburg quarry and then the Mount Pleasant Mills No. 2 quarry, but the wavellite itself is reported from the upper bench at Mount Pleasant Mills.
The locality’s collecting history has several clear phases. The quarry was already a collector destination for calcite, strontianite, fluorite, celestine, and fossils before wavellite became the headline species. Wavellite was discovered by the owner around 2000 or in the early 2000s, and the first collector activity followed after local rockhounds confirmed the identity. Specimens were being documented by collectors and on Mindat by 2007–2008, and the locality appeared in the Rochester Mineralogical Symposium literature in 2011. Excavation around 2012 produced lustrous micros from deeper work in the wavellite area. Bill Stephens’ collecting and mapping interest began around 2015, when an adit was open and veins could be worked in solid rock rather than only in old spoils. Major machine-assisted work in 2022 reopened and documented the western wavellite pit, and another machine dig in March 2024 extended the workings eastward and downward, recovering hundreds of specimens and exposing the yellow-dominant “Lemon Drop” zone.
Notable finds include cabinet-size and larger matrix specimens, strongly chartreuse radial aggregates, green-and-colorless lobed crystal masses, botryoidal material with unusual banding, fossil cavities filled with quartz crystals and wavellite, and a 2024 yellow zone that produced the locality’s much-discussed larger free-standing yellow balls. The locality is also notable for phosphate diversity: laboratory-confirmed associated phosphates include planerite, turquoise, variscite, vauxite, and cacoxenite.
Mount Pleasant Mills wavellite is best known for hemispherical to spherulitic aggregates, botryoidal crusts, and circular radiating sprays on sandstone. Individual crystal terminations are usually tiny, but good pieces show a crisp fibrous or acicular radial structure under magnification. Broken or naturally open hemispheres may reveal the classic wavellite structure: fibers radiating inward from the outer surface toward the center. On matrix, this can look like tiny round green buttons; in cross-section, it becomes a fan, flower, or “rising sun.”
The color range is central to the locality’s appeal. Mindat summarizes the occurrence as off-white to pastel green, but collector material spans colorless, white, pale yellow, lemon-yellow, yellow-green, apple-green, chartreuse, and darker green. Recent analytical work on field-trip material found that the green color in Lime Ridge wavellite is caused by vanadium; colorless wavellite analyzed from the same collecting event lacked vanadium. The 2024 machine dig documented a shift from darker green material toward yellow material in the “Lemon Drop” zone.
Typical individual wavellite masses are small. A 2025 fluorescence study described yellow-green spherulitic masses and radiating fibrous forms generally measuring 1–16 mm on tan sandstone matrices. Mindat photo records show specimens with crystal aggregates around 3–4 mm as well as matrix pieces in the 5–10 cm range. Larger display pieces are very real: documented examples include specimens around 10.5 x 7.0 x 3.2 cm, 11.6 x 7.0 x 2.8 cm, 13.2 x 12.7 x 4.2 cm, and a large photographed piece measuring 21.1 x 11.7 x 5.5 cm. One 2024 field abstract notes a 1-inch yellow ball matrix specimen as the largest free-standing individual crystal known to the presenter at that time.
The matrix is usually sandstone or quartz arenite, not the dark ironstone-like matrix that collectors may associate with some Arkansas wavellite. This is a useful visual clue. The best Mount Pleasant Mills specimens show green or yellow wavellite perched on pale tan, buff, or grayish sandstone, sometimes with small quartz crystals, limonite staining, or fossil textures. Fossils are not incidental: the Ridgeley Member is fossiliferous, and field-trip reports record brachiopods, gastropods, pelecypods, trilobites, crinoids, and fossil impressions. Some fossil cavities acted as protected growth sites for wavellite and cacoxenite, and at least one documented fossil contained both quartz crystals and a 1.1 cm wavellite sphere.
Associated minerals vary depending on whether one is discussing the quarry as a whole or the wavellite pits specifically. In the quarry, collectors encounter calcite, strontianite, celestine, fluorite, dolomite, and fossils. In the phosphate zone, wavellite is associated with cacoxenite, planerite, variscite, turquoise, vauxite, and quartz. Cacoxenite is especially important at the micro level, where collectors have reported acicular sprays and balls of both wavellite and cacoxenite in fossil impressions and sandstone cavities.
Quality factors are straightforward but demanding. The finest specimens combine vivid color, intact hemispheres, lustrous or satiny radial surfaces, and a strong composition on matrix. Damage is common because wavellite balls and sprays project from sandstone and can bruise, cleave away, or lose their delicate outer fibrous surfaces during extraction. Pieces with scattered, isolated balls can be more aesthetic than solid crusts if the spacing is graceful. Specimens with color contrast—green beside colorless, yellow beside white, or chartreuse on pale quartz-rich sandstone—are especially collectible. Micros with sharp, open acicular sprays can be excellent even when the hand specimen looks modest.
Fluorescence is an additional specialty interest. A 2025 study of fourteen specimens from the property reported fluorescence in all specimens tested under shortwave 254 nm, mid-wave 312 nm, longwave 351 nm, and longwave 370 nm lamps, with responses varying from low to moderate-bright blue-green or emerald-green. Most specimens showed low-intensity fluorescence, and most also showed some phosphorescence, although one tested specimen did not. Longer wavelengths generally produced more vivid results in that study.
Authentic Mount Pleasant Mills wavellite should be evaluated as a locality specimen, not merely as “green wavellite.” The best indicators are matrix, habit, and association: yellow-green to apple-green spherulitic or radiating wavellite on tan Ridgeley sandstone, often with quartz, limonitic staining, fossil textures, or other phosphate minerals. Arkansas wavellite, while superficially similar in spherical habit, usually has a different color range, matrix character, and collecting history. Color alone is not enough for authentication because Mount Pleasant Mills naturally produces colorless, white, yellow, yellow-green, and green material.
No recurring, named fake problem specific to Mount Pleasant Mills wavellite is documented in the collector literature consulted for this guide. The more realistic concerns are mislocality, overcleaning, and condition. Because wavellite is a well-known collector species from Arkansas and several other localities, older labels should be read carefully. A credible label should distinguish National Limestone Quarry No. 2, Lime Ridge, Mount Pleasant Mills, Perry Township, Snyder County, Pennsylvania, from nearby or regional Pennsylvania phosphate localities such as Kreamer or other wavellite occurrences.
Treatment concerns are modest but worth noting. One Mindat-documented specimen from excavation around May 2012 is explicitly described as having rust removed with oxalic acid. Oxalic acid cleaning is common in mineral preparation and is not inherently deceptive when disclosed, but it matters for this locality because iron staining is part of the natural sandstone environment. A specimen that is unnaturally pale, chalky, or stripped-looking may have been overcleaned. Conversely, one Mindat specimen with unusual “gooseberry” banding is explicitly described by its collector as found with no special cleaning or bleaching, underscoring that unusual color patterning can be natural at this locality.
Condition is the main grading issue. Wavellite aggregates are fibrous and projecting; balls can be contacted, flattened, abraded, or partly detached. On cabinet pieces, look closely at the highest points of the hemispheres, the edges of radial fans, and any exposed cross-sections. A few contacted balls on a large plate may be acceptable if the overall composition is strong, but premium specimens should show intact surfaces and minimal bruising. Sandstone matrix can be friable, so old repairs, glue stabilization, and trimmed edges should be inspected under magnification.
Rarity is tiered. Small pieces and modest botryoidal crusts are obtainable, especially from club-collected material and recent machine-dig dispersals. Good miniatures and small cabinets with sharp color, clean matrix contrast, and intact hemispheres are significantly scarcer. Large, aesthetic cabinet specimens with vivid yellow-green or lemon-yellow wavellite, strong relief, and minimal damage are genuinely uncommon. The 2022 and 2024 machine digs improved availability, but the locality remains access-controlled, structurally localized, and dependent on club trips or organized work; it is not a public collecting area producing a steady commercial flow.
Market availability is intermittent. Recent online and dealer records show specimens ranging from tiny thumbnail material to cabinet pieces, with stronger large pieces offered by established dealers and aggregators. The most desirable examples command a premium because they combine an unusual Pennsylvania locality, attractive color, documented modern collecting history, and a look that differs from the standard Arkansas material most collectors already know.
The Mount Pleasant Mills wavellite story begins with a quarry owner noticing the wrong color in the right place. Around the beginning of the 2000s, Eric Stahl was clearing or improving a perimeter roadway on the upper bench of National Limestone Quarry No. 2, along the southern property line. There, in the steep sandstone beds just over the ridge from the limestone workings, he saw “green.” He brought in local rockhounds and expert collectors to investigate. They dug, recognized the habit, confirmed the species as wavellite, and the secret did not stay secret for long. Clubs began asking for permission, and a quarry previously known mainly for calcite, strontianite, fluorite, celestine, and fossils suddenly had a phosphate occurrence with national-level potential.
By October 29, 2016, the locality had become a serious club destination. A field trip to National Limestone Quarries No. 1 and No. 2 brought about twenty people from four or five regional EFMLS clubs, including groups from Delaware, Montgomery County in Maryland, Baltimore, Southern Maryland, and Northern Virginia. At No. 2, collectors worked the two hilltop wavellite sites. The report from that day describes “very energetic digging” and only a few hand-size specimens of botryoidal green wavellite, but the real prize was under the microscope: acicular sprays and balls of wavellite and cacoxenite, both as spheroidal growths and space-filling forms. Brachiopod fossils were abundant, and some fossil impressions had become sheltered little phosphate chambers where wavellite and cacoxenite crystallized sharply enough to reward careful micro collecting.
Bill Stephens first visited the wavellite occurrence around 2015 and found it unusually productive. The important detail is that the adit was open. Instead of scraping through old spoil, collectors could reach veins in solid rock, and that changed the quality of what could be recovered. Stephens later wrote that he and others got “killer specimens.” He began building a PowerPoint presentation and returned to the locality repeatedly, but his broader effort to map and document the occurrence was interrupted: first by a death in the family while onsite, then by work demands, and then by COVID. The locality waited.
In 2022, Stephens returned with a plan. The site and road had become overgrown, and short half-day club trips were no longer exposing fresh specimens. Before the first club trip scheduled for April 9, 2022, he arranged and paid for excavation work with Eric Stahl. Stahl’s son cleared the road so it would be passable for any vehicle, removed waste overburden, and expanded the hole downward and eastward. Spoils were used to soften the grade change in the roadway and to build room for a track-hoe pad over the old mined-out area. The machine-assisted excavation and documentation of wavellite veins took five days spread over about a month.
That 2022 work was not just a specimen dig. Stephens used the reopening to study structure. Drone mapping followed, constrained by surveyed ground-control points to build a high-resolution color orthomosaic and 3D model of the quarry. Strike-and-dip measurements on bedding, joints, and fractures were taken remotely with a Total Station, using a modified spreadsheet method so structural measurements could be calculated in places too inaccessible for direct measurement. The emerging interpretation was that the collectible minerals were controlled by brittle deformation: calcite, fluorite, strontianite, and celestine in the carbonate rocks related to one structural history, and the phosphate mineralization in the Ridgeley beds representing a later, post-Alleghenian epigenetic event.
The November 13, 2022 Friends of Mineralogy Pennsylvania Chapter field trip added a quieter but scientifically memorable chapter. Ronald A. Sloto examined material from the Lime Ridge wavellite locality and found something he had not seen there before: massive orange planerite forming veins in sandstone in the west wavellite pit. The veins were up to 1 cm thick, and SEM-EDS analysis showed the orange mineral to be planerite, with the orange color likely caused by 2.22 wt % iron. The same trip produced abundant colorless wavellite in thin fracture veins; when the veins were split, the wavellite showed radiating patterns, but the fractures were too narrow to allow spheres or partial spheres to form. Sloto’s analyses also sharpened the color story: green wavellite contained vanadium, colorless wavellite did not.
That field trip also showed how fossiliferous the Ridgeley sandstone can be. Some fossils were filled with clear quartz crystals, and one quartz-filled fossil resembled a miniature geode. Another contained quartz crystals and a wavellite sphere. The documented specimen was only 4 cm across, but the wavellite sphere inside measured 1.1 cm, with interlocking terminations visible on the outside of the ball. It is exactly the kind of small, specific occurrence that makes Mount Pleasant Mills more than a “green ball” locality: fossil, quartz, sandstone, phosphate chemistry, and open space all converged inside a Devonian shell.
In March 2024, the locality changed again. A second machine dig moved from the eastern limits of the west pit about 35 feet east and as much as 20 feet below the road level. Ryan Klockner of Geology365 had been involved in the 2022 work, and the 2024 dig included Tommy Greene, known as “The Craft Miner,” of the North Jersey Club. Andrew “Rockhound” Eppig took off the week to video-document the mining effort. Hundreds of specimens were recovered. The memorable shift was color: from darker green toward yellow, until yellow became dominant in a zone the diggers called the “Lemon Drop” zone. Ryan’s 1-inch yellow ball matrix specimen remained, in Stephens’ account, the largest free-standing individual crystal known from the work. By the end of the 2024 dig, the Lemon Drop zone had been completely dug out, and the eastern adit had been reopened and was producing wavellite.
The locality has also had less glamorous days, which are part of the honest life of a quarry occurrence. A January 2025 Nittany Mineralogical Society report described field-trip participants driving more than two hours east to gather at National Limestone Quarry, Inc., in Mount Pleasant Mills. Rain impeded collecting, and no new material had been exposed in a while, but specimens were still collected. That is the rhythm of Mount Pleasant Mills: spectacular when fresh sandstone and phosphate seams are opened, stubborn when the pits are stale, and always dependent on the quarry owner’s permission and the discipline of organized club access.
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