Other Quartz Modifications       Rarely, quartz crystals from this locality will show additional modifications to the basic form.  The most common of these modifications is the trigonal bipyramidal “s” face.  This face occurs at the intersection of two prism faces and two rhombohedral faces.  An example of this modification is displayed in the photo to the right.  The  2nd generation crystal with 2nd order prism face crystal measures 7 mm Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio “s” face modification has only been observed on crystals from the 2nd generation of quartz.  Crude second order prisms have also been observed on 2nd generation quartz crystals.  These prism faces are typically very slight and occur in pairs, often incomplete, between two first order prism faces.  A larger than average second order prism can be seen on the quartz crystal in the photo to the left.

2nd generation quartz crystal with trigonal bipyramidal s face (specimen Joseph W. Vasichko) s face measures .3 mm  West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio

Quartz var. Chalcedony       As mentioned previously, the first generation of quartz occurs as isolated growths of snow white botryoidal chalcedony.  This generation of quartz is by far the most seldom generation encountered.   Spotty sulfide minerals, especially pyrite, are often intergrown and dusted on the  drusy quartz over chalcedony chalcedony is 4 mm across Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio chalcedony , as is evident in the photo to the right.   This first generation chalcedony is typically coated with crusts or seams of drusy multigrowth second generation quartz.  An example of the first two generations of quartz is displayed in the photo to the left.   As is true of this specimen, much of the chalcedony at this locality can only be observed on the broken edges of specimens.  Although the second generation quartz appears to radiate away from the chalcedony, chalcedony does not have a radiating structure.

1st generation quartz var. chalcedony dusted with pyrite (specimen Joseph W. Vasichko) field of view is 1.8 cm x 1.1 cm West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio

2nd Generation Quartz       Quartz crystals from the 2nd generation occur in a number of different habits including individual multiple growth crystals, clusters of radiating multiple growth crystals or flower quartz and thick seams or crusts of drusy multiple growth crystals.  In general, crystals from this generation are vitreous but internally clouded.  The most aesthetic examples from this generation are individuals and clusters resting on second generation ferroan dolomite.  An example of a multiple growth flower quartz cluster is displayed in the photo to the upper right.  The 2nd picture to the right exhibits a classic specimen of 2nd generation quartz crystals sprinkled on second generation ferroan dolomite.  Most quartz crystals from this generation typically have moderately to severely etched prism faces.  This is generally more pronounced in larger crystals.  Smaller crystals will typically have a series of etched, graphic markings on the  etched 2nd generation quartz crystal (specimen Joseph W. Vasichko) crystal measures 5 mm West branch of the Huron River  at Lamereaux road bridge Monroeville, Huron Co., Ohio 2nd generation quartz crystal showing x-shape (specimen Joseph W. Vasichko) crystal measures 1.3 cm West branch of the Huron River  at Lamereaux road bridge Monroeville, Huron Co., Ohio 2nd generation hourglass quartz crystal  (specimen Joseph W. Vasichko) crystal measures 1.1 cm West branch of the Huron River  at Lamereaux road bridge Monroeville, Huron Co., Ohio prism faces perpendicular to the terminations of the crystal.  The photo to the upper left displays a smaller crystal with these markings.  An X-shape is often formed on the prism faces of crystals from this generation, because of the parallel multiple growth habit.  In some smaller crystals, this X-shape is reduced to a set of notches on the prism face as seen in the photo to the upper left.  In larger crystals from this generation, the etched markings are heavier through the center of the prism faces, as seen in the second photo to the left.  The multiple terminations of larger crystals tend to angle slightly from the center of the crystal amplifying the X-shape of the prism faces.  In extreme cases, the terminations of the crystal appear to be two separate crystals, grown in parallel and terminated into one another.  On these crystals the X-shape is expanded into an hourglass shape.  An example of this is pictured to the lower left.  The prism faces are commonly highly etched on these crystals.  Although isolated crystals from this generation are generally less than 2 cm in size, larger crystals are often found in thicker seams.  When these seams open into pockets, crystal points alone up to 2 cm across have been observed.  Specimens of drusy quartz are generally more clouded than individual crystals.  This is more likely due to the larger size of the crystals, than the habit.  A typical example of drusy quartz from the 2nd generation is pictured to the lower right.  This habit is one of the more common and least desirable occurrences of quartz at the Monroeville locality because the crystals are less distinct.

multiple growth flower quartz on ferroan dolomite (specimen Joseph W. Vasichko) quartz flower measures 1.3 cm West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio 2nd generation quartz crystals on ferroan dolomite (specimen Joseph W. Vasichko) specimen measures 8.8 cm x 4.6 cm West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio 2nd generation drusy quartz specimen measures 8.7 cm x 7.9 cm (specimen Joseph W. Vasichko) West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio

3rd Generation Quartz      The most highly sought quartz specimens from the Monroeville locality are those of 3rd generation crystals.   Crystals from the third generation are often more distinct with sharper faces than crystals from the 2nd generation.   These crystals range from water clear, milky gray to smoky black.   Many local collectors refer to these as Huron diamonds due to their similarity to Herkimer diamonds, though Herkimer diamonds are generally clearer, more abundant and can be much larger.  Although crystals less than 5 mm in size are the norm at the Monroeville locality, individuals up to 3 cm have been observed.   Any complete crystal from this generation of good form, larger than 1 cm and on matrix should be considered a prize.   A better than average, cabinet size example of 3rd generation diamond like crystals on matrix is displayed in the photo to the upper right.  The 3rd generation of quartz also formed after a no longer present occurrence of Anhydrite.   Several examples of micro quartz crystals forming platy casts of large Anhydrite crystals have been observed.  These thin casts are very delicate and are often incomplete.  A typical example of this occurrence is displayed  micro quartz crystals, pseudo after anhydrite (specimen Joseph W. Vasichko) field of view is 2.6 cm x 1.8 cm Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio quartz crystals with sediment inclusions (specimen Joseph W. Vasichko) field of view is 1.6 cm x 1.2 cm Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio doubly terminated smoky crystal (specimen Joseph W. Vasichko) crystal measures 1.5 cm Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio in the photo to the upper left.  Casts of 3rd and 4th generation ferroan dolomite after anhydrite are also common.  Occasionally, quartz crystals from this generation will be partially included with sediment or clay.   This causes the crystals to be tan in color.  An example of this is exhibited in the photo to the middle left.  Larger 3rd generation crystals are generally more heavily clouded than small crystals which are often water clear.    The photo to the middle right displays this characteristic of 3rd generation crystals.  Notice that many of the smaller accessory quartz crystals are much clearer than the largest crystal.  Occasionally crystals from this 3rd generation are an attractive smoky black color.   The exact cause of this coloring has not been identified, but may be a result of higher levels of uranium in the Huron Shale.  Over a long period of time, exposure to small amounts of radiation from the surrounding shale may have darkened these crystals.   However, this may not be the cause as only a small percentage of 3rd generation crystals are smoky and no crystals from the 2nd generation have been observed with this coloring.  It has also been hypothesized that thin inclusions of marcasite may be the cause.  In either case, these smoky crystals are unique and unlike most Ohio quartz.  Typical smoky quartz crystals are displayed in the photos to the lower left and lower right.

water clear quartz crystals on ferroan dolomite (specimen Joseph W. Vasichko) specimen measures 11.1 cm x 9.8 cm West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio slightly milky gray and clear quartz crystals on ferroan dolomite (specimen Joseph W. Vasichko) specimen measures 5.8 cm x 4.2 cm West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio smoky quartz crystal on ferroan dolomite (specimen Joseph W. Vasichko) specimen measures 3.2 cm x 3.1 cm West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio

CALCITE CaCO3       While the Monroeville locality is best known for its quartz and ferroan dolomite, it does occasionally yield good specimens of several other species including calcite.  Calcite is one of Ohio’s more diverse minerals, due to the numerous crystal forms the mineral is known produce.   Even within the borders of Ohio, the variety of calcite occurrences is limitless and new habits are still discovered by field collectors today.  While the Monroeville site is certainly not one of Ohio’s premier calcite localities, true Ohio collectors would agree that while crystals from this locality are not as impressive, these crystals are equally important as specimens from the Custar Stone quarry in Wood County or the Sylvania quarry in Lucas County.  Typically, calcite crystals range from 1 to 5 cm in size.  However, calcite crystals up to 20 cm have been reported from septaria at this locality, though rarely complete at that size.  These crystals vary in form, color and clarity but are often found attractively resting on slightly color-contrasting ferroan dolomite.  Crystals can be white, tan, brown, gray or clear and are generally complex scalenohedrons or prisms, each with rhombohedral terminations, or rounded scalenohedrons.  The majority of calcite crystals found at this locality have crude, etched or melted, and uneven faces.

Calcite on 4th generation ferroan dolomite (specimen Joseph W. Vasichko) specimen measures 7.4 cm x 4.2 cm West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio

complex scalenohedral calcite on ferroan dolomite (specimen Joseph W. Vasichko) specimen measures 5.3 cm x 3.6 cm Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio

Calcite Occurrence      Throughout the state, the large septaria in the Huron shale are often chiefly comprised of limestone, bearing thick calcite veins with occasional ferroan dolomite.  At the Monroeville locality, calcite is the less common vein mineral.  In fact, many of the septaria at the Monroeville locality contain little or no calcite.   Calcite, when present, generally forms small isolated crystals.  Most of the calcite which has been observed at the locality formed after the 5th generation of ferroan dolomite but before the 6th generation of ferroan dolomite.  This places the main calcite event after the last generation of quartz.  Specimens of calcite over quartz are regularly found at the locality.  In fact, the calcite in the photo to the left has a large impression in the back where a smoky quartz crystal had been attached.   An earlier calcite event occurred after the 2nd generation of quartz.   Most of the calcite from this first generation is light tan to brown colored and opaque and typically less attractive.  This generation  forms veins of small intergrown crystals.  These veins of calcite are more friable than calcite from the 2nd generation.   Rarely, these veins open into pockets with light tan scalenohedral crystal clusters.  It should be noted that small isolated scalenohedral crystals also occur in the 2nd generation of calcite.  Thus, the form alone does not indicate the generation.  It is common to find calcite in combination with other minerals, especially quartz.  The photo to the right displays a typical example of calcite with 3rd generation quartz on 5th generation ferroan dolomite.   Note that the ferroan dolomite is grown over the quartz. calcite, quartz in ferroan dolomite pocket (specimen Joseph W. Vasichko) Calcite crystal is 1.0 cm across Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio

Calcite Crystal Forms       Four distinct crystal forms have been observed on calcite crystals from the Monroeville locality.  The most commonly observed calcite crystals are either scalenohedral with negative scalenohedral modifications and rhombohedral terminations as illustrated by crystal A in figure V to the right or prismatic with large rhombohedral terminations.  Many of the prismatic crystals have negative rhombohedral modifications and scalenohedral modifications as illustrated by crystal B to the right.  Occasionally, crystals will have 12 prism faces as seen in crystal C.    These are dihexagonal prism faces and not 1st and 2nd order prisms.   Specimens with 1st and 2nd  flattened stacked rhombohedral calcite (specimen Joseph W. Vasichko) field of view is 7 mm x 4 mm Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio order prism faces may occur, but have not been identified.  Small flattened rhombohedrons,  sometimes stacked as in the photo to the left, also occur in the 2nd generation.  Another calcite form infrequently seen at this locality is the basic scalenohedron, illustrated as crystal D to the right.   Scalenohedral crystals have rounded faces and are often indistinct.  Scalenohedral crystals from the 1st generation are very unlike crystals from the 2nd generation both in crystal form and other physical properties.  Fig V.  forms of calcite crystals.  A) positive scalenohedron(v) with  negative scalenohedron(x) and positive rhombohedron(r).  B)  prism(a)  with positive and negative(e) rhombohedron and positive scalenohedron.  C) dihexagonal prism(a) with positive and negative rhombohedron and  positive scalenohedron.   D) scalenohedron.

dihexagonal prism with rhombohedral termination. (specimen Joseph W. Vasichko) crystal measures 2.3 cm  West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio calcite on 4th and 5th generation ferroan dolomite (specimen John D. Vasichko) specimen measures 8.9 cm x 6.1 cm West branch of the Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio

Complex Calcite Crystals      The largest and most aesthetic calcite crystals found at the Lamereaux road bridge locality are the more common complex crystals from the 2nd generation, as illustrated by crystals A, B and C in figure V.  Crystal forms A and B appear more frequently than crystal C.   These slightly translucent crystals vary from white to milky gray to chocolate brown in color and are occasionally zoned from white to brown as the crystal in the photo to the  upper right.  Crystals less than 1 cm in size are occasionally mostly clear.  It is often difficult to discern the exact dominant form of these crystals due to their inherent globular shape and melted, indistinct faces.   Crystals that are elongate are more easily identified, than shorter crystals.  Generally, the only easily identifiable faces are the rhombohedral terminations.  The photo to the upper left displays the common rhombohedral termination found on these crystals.  This particular crystal also happens to be dominated by the dihexagonal prism.  Many of these crystals appear formless in contrast to the sharper crystals of ferroan dolomite.  The photo to the lower left displays a typical example of this effect.   From a distance, it appears to be a rounded calcite mass.  However, upon close inspection this crystal is scalenohedral with negative scalenohedral modifications and rhombohedral terminations.  The clear, gray and white crystals of this form often show a distinct pale reddish pink fluorescence under short wave ultraviolet light and a stronger red fluorescence under mid wave ultraviolet light.  An example under mid wave is displayed to the lower right.  Some etched crystals also display a very pale blue white fluorescence. zoned calcite crystal (specimen Joseph W. Vasichko) crystal measures 1.0 cm  Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio calcite under MW UV light (specimen Joseph W. Vasichko) crystal measures 1.5 cm  Huron River at Lamereaux road bridge Monroeville, Huron Co., Ohio