by Harold (Fritz) Moritz

Specimen MP-03. Field of view 22mm. Mike Polletta specimen. H. Moritz photo.

Recently I submitted samples of chabazite group crystals from several places around Connecticut for analyses. Micromounters New England will perform a limited number of scanning electron microscope – energy dispersive spectroscopy (SEM-EDS) analyses for members such as me.  SEM-EDS provides elemental chemistry on extremely small samples except for the very light elements H, He, B, Be and Li.

The goals of this project were to better determine the particular species of chabazite on the specific samples and from that information hopefully extend the species identifications to unanalyzed specimens from the same localities, and perhaps throughout the state.  Consequently, at least one sample was selected from most known localities with 2 samples submitted from the very prolific O&G locality.  

Originally described as one mineral in 1788, the chabazite group of zeolite minerals has been divided into 5 similar-looking species - chabazite-Ca, chabazite-K, chabazite-Mg, chabazite-Na, chabazite-Sr, with most of them having the general formula (A)2[Al2Si4O12]2 · 12H2O, where the A site can be occupied by Ca, K2, Na2, and/or Sr.  The particular species depends on the relative proportion of the element in the A site.  Chabazite-Mg has a slightly different formula.  In general, according to mindat.org, chabazite-Ca appears to be by far the most common species, with chabazite-Na, chabazite-K relatively uncommon, and chabazite Mg and chabazite-Sr very rare.  However, some of the disparity may be due to a lack of analyses.  But with few if any published modern analyses of local samples, anything could be found.
Below is a table of the samples (most from my collection except MP03) followed by a discussion of the results.

Chabazite crystals occur in Connecticut only at a few places in the basalt flows (trap rock) where there is significant mineralization in gas vesicles and fractures.  These are primarily the two O&G quarries in Woodbury (No. 1) and on the Woodbury/Southbury line (No. 2).  It is also less commonly found at the quarry at Reed’s Gap on the Durham/Wallingford line and at the old Cheshire Quarry.  In this geo-environment it typically occurs with pumpellyite, calcite, quartz, babingtonite, apophyllite-K, and other zeolite group minerals (stilbite, heulandite, analcime, natrolite).  Attractive specimens have been saved from these localities.

Chabazite can also rarely occur in fractures in metamorphic rocks with other zeolite minerals, typically stilbite.  Several places have yielded many crystals, particularly the old Route 6 bypass in Newtown that became part of I-84, at road cuts in Harwinton and Watertown, and at outcrops at the Tailwaggers, Inc. property in Litchfield.
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All of the SEM-EDS results shown below found the chabazite-Ca species, with K and Na also detected in most, but not enough to change the species.  Interestingly, the specimens from trap rock geo-environments (313, 1403, 1873) included, according to the SEM-EDS operator Peter Cristofono, “minor K, and trace Na” while those from fractures in metamorphic rocks included “significant K, and minor Na” or Mg (1774, 1871, 2526, MP03).  The latter tend to have a yellow-orange color, probably from a tiny amount of Fe, too low to show up in the EDS spectra. Thus there is some apparently consistent minor difference in the mineral’s chemistry between these two geo-environments.  In any case, I think it is reasonable to conclude that any chabazite found elsewhere in the state should belong to the chabazite-Ca species, unless it is identified at a new locality that has a very different mineral-forming geo-environment than the ones above.  In that case, a full analysis should be done.

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​Specimen 313
Rhombohedral chabazite-Ca crystals on quartz filling in gaps between dissolved tabular anhydrite molds. 

Field of view 17mm. H. Moritz photo.

Specimen 1403

​Clusters of dark, pseudocubic chabazite sit next to colorless, pearly heulandite (center and right) and frosty calcite (lower left) in a spray of tabular voids left by dissolved anhydrite in white chalcedony ​agate. 

Field of view 26mm. H. Moritz photo.

​Specimen 1774
Chabazite-Ca crystals on a fracture surface in schist, very surprisingly these crystals fluorescence green under short-wave ultraviolet light. 

Field of view 4.5 cm. H. Moritz photo.

​Specimen 1871
Yellow-orange chabazite-Ca and white stilbite (upper right edge) crystals in a fracture in amphibolite.  

Field of view 20mm. H. Moritz photo.

​Specimen 1875
Complex, multiple interpenetration twinned chabazite crystal on calcite, typical of the one from the same piece used for the analysis. All of them are microscopic.  

Field of view 2.69mm. H. Moritz photo.

​Specimen 2526
Yellow-orange rhombohedral chabazite-Ca crystals with white calcite on annite gneiss. 

Field of view 2.5cm. H. Moritz photo.

Specimen MP-03
Yellow-orange chabazite-Ca with pyrite and white calcite in a fracture in granofels. 

Field of view 22mm. Mike Polletta specimen. H. Moritz photo.

Specimen 708
Pinkish-white apophyllite-(K) with drusy, tabular datolite. FOV 5 cm tall.

 H. Moritz photo.

By Dickson Cunningham, [Chair] Department of Environmental Earth Science at Eastern Connecticut State University.

The Department of Environmental Earth Science at ECSU continues to grow from strength to strength with a number of notable achievements during the last 24 months.   We continue to offer a diverse undergraduate curriculum focusing on earth science, sustainable energy and environmental science.  As part of our ongoing efforts to develop experiential learning opportunities for our 90-100 majors, we have expanded our undergraduate field-training program.  In May 2016, we took 16 students to Iceland for 10 days to investigate the island’s spectacular volcanology, glaciology, geomorphology, active tectonic features and renewable energy industry.  The trip included exciting hikes through the Thingvellir rift zone, various geothermal sites, glaciers in Skaftafell National Park, a visit to Heimaey in the Vestmann Islands and a boat ride through the Jökulsárlón ice lagoon.   The department also ran a separate 10-day trip in 2017 to Arizona, with visits to many of the state’s geological highlights including the Grand Canyon, the San Francisco Volcanic Field, Sedona, Petrified Forest/Painted Desert, Saguaro National Park, the Santa Catalina Mts, Montezuma Castle,  Wupatki pueblo, the Asarco Mining operation south of Tucson and the Jerome mining ‘ghost town’.   We now have in place an exciting range of field courses that will rotate in coming years.  We are also currently developing new field trips to Spain and New Hampshire/Maine.
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Because of the educational value of out-of-classroom learning experiences, we also continue to develop our program of undergraduate research and internship involvement.  The Department receives substantial university support to engage our majors in supervised research projects with real-world significance. Ongoing projects include investigating coastal erosion, storm records and shoreline change on the Rhode Island coastline and Block Island (advisors, Oakley, Hyatt, Nathan), the sedimentology, paleo-ecology and geothermal properties of Hartford Basin stratigraphy (advisors: Drewiecki, Nathan, Hyatt), arsenic contamination in eastern CT groundwater (Advisor: Metcalf), litho-tectonic evolution of SE CT bedrock terrain (Cunningham), and sustainable energy use in local communities (Torcellini).  In addition, a handful of students hold internships at the ECSU Institute of Sustainable Energy focusing on campus energy use issues.  An exciting new collaborative internship program with DEEP has involved more than 12 students in GIS-related land use projects in the last year.

Our students have distinguished themselves at numerous professional conferences in the last 18 months such as GSA, COPLAC, NCUR, and at the annual ECSU undergraduate research conference.  Independent faculty research has also published in leading journals and presented at numerous national and international meetings including invited lectures and keynotes at AGU, 50th anniversary of Plate Tectonics meeting in London, SNET (Brazil), and a large number of sustainable energy meetings and workshops including the annual meetings of the Association for the Advancement of Sustainability in Higher Education (AASHE) and the American Society of Heating, Refrigerating, Air-Conditioning Engineers (ASHRAE).  Professors Torcellini and Oakley have also recently secured significant external grant funding to support their research into sustainable buildings and coastal geology, respectively.

As the job market evolves, we continue to update our curriculum to meet employer needs.  We have recently introduced a new Environmental Health Science minor, revamped the sustainable energy science concentration and developed a new AutoCAD course.   Finally, in spring, 2018, we successfully petitioned for a new chapter of the Sigma Gamma Epsilon National Honor Society in the Earth Sciences and in May we will induct our first 17 student members.

Text and photos by Harold “Fritz” Moritz

Amphiboles are important and widespread rock-forming minerals in the metamorphic rocks of
the highlands of Connecticut. Most of their specific characterization has been documented via
optical microscopy using thin-sections and published in bedrock geological quadrangle reports
since the 1950s. In less common instances, they can be found as large, distinct and collectible
crystals begging for detailed characterization. To date, most local amphiboles are identified as
tremolite (white to colorless), actinolite (green), hornblende (very dark green to black), or
anthophyllite (brown to green-brown in the Middletown Formation). The International
Mineralogical Association’s (IMA) many changes in nomenclature post-date most of the
literature about them in this state and so many more recognized species potentially exist based on
IMA’s subdivisions of earlier ones. To remedy this situation, during August 2016 and March
2017, I submitted samples of Connecticut amphiboles (or suspected ones) to Frank Craig for
TEM-EDS analyses. Frank is preparing an atlas of amphiboles and I am interested in
determining the various species found in Connecticut.

Amphiboles are extensive and complex group of minerals presently divided into a group/subgroup/root-name hierarchy and with either monoclinic (more common) or orthorhombic crystal symmetry. The latest IMA nomenclature report (Hawthorne et al., 2012) uses the general formula AB2C5T8O22W2 where:
A = ☐, Na, K, Ca, Pb2+
B = Li, Na, Mg, Fe2+, Mn2+, Ca
C = Li, Na, Mg, Fe2+, Mn2+, Zn, Co, Ni, Al, Fe3+, Cr3+, Mn3+, V3+, Ti, Zr
T = Si, Al, Ti
O = oxygen
W = O, OH, F, Cl

Individual members can often only be completely identified by a combination of chemical-analytical, X-ray diffraction and spectroscopic methods.  However, TEM-EDS is a very powerful method that can by itself provide a wealth of chemical information to differentiate species, especially involving the A, B, C and T sites.  In the list of elements above, the TEM-EDS method can cannot detect Li and H, so full characterization of the W site’s constituents is lacking and species cannot be split at that level.  Li-containing amphiboles are rare and not expected in Connecticut.  Nearly all amphiboles are monoclinic, so X-ray diffraction is rarely necessary so long as the samples are correctly visually identified as amphiboles, except in the case of differentiating the paramorphs anthophyllite (orthorhombic) from cummingtonite (monoclinic).  But where that ambiguity exists, selected area electron dispersion (SAED) can be used. 

Below is a table of the samples, their suspected identification, the method used, and the results, followed by a discussion of each sample.  The spectra were acquired by Frank Craig on a JEOL 100 CXII transmission electron microscope using an accelerating voltage of 100 KeV and a spot size <500 nm with light element EDS detector.  Data reduction used Locock, A. J. (2014), An Excel spreadsheet to classify chemical analyses of amphiboles following the IMA 2012 recommendations. Computers and Geosciences: 62: 1-11.  The oxide weight percent was adjusted to allow for anions occupying the W site.  Amphiboles typically have 1.5% to 2.5% (OH), values are normalized to 1.75% (not included in total).  Much of the resulting data have been included in the upcoming second edition of Frank Craig’s Asbestos Characterization, TEM Atlas of Regulated and Select Interference Minerals. 

Samples

Sample 534:  A dark greenish-black amphibole, probably a “hornblende” found at a construction site along East Main Street in Waterbury about 150 meters from the Cheshire line, in a calc-silicate rock associated with scapolite series and titanite.  TEM-EDS results indicate it is magnesio-hornblende

Sample 3035:  A sample of amphibolite from the Middletown Formation collected by Richard Schooner from an outcrop along the power line right-of-way in East Hampton between Hurd and Seymour State Parks.  He had labeled it as “riebeckite” likley because of its generally fine-grained nature (full view - 18.5 x 12 x 1.5 cm, close-up – FOV 6 cm).  I wanted to confirm or refute this identification.  The TEM-EDS results show that it is magnesio-hornblende.

Sample 3478:  A specimen of unaltered amphibolite hosting scheelite in the are of Old Mine Park in Trumbull, the TEM-EDS results indicates it is magnesio-hornblende.

original identification.  However, the TEM-EDS results indicate it is actually our friend magnesio-hornblende, although the subsamples do trend toward the actinolite field.

of hand samples with mineral identifications.  It does say that both are present as large crystals in the Middletown Formation, which is well exposed in Haddam and Chester.  Anthophyllite is typically described as brownish, though the material I always see in the field is greenish, while gedrite is described as black.  The TEM-EDS results indicate it is anthophyllite.

Samples 1017 and 1019:  Searching for the gedrite described in the Lundgren’s 1979 Haddam Quadrangle bedrock geological report, in 2016 I went to an area “south of Turkey Hill Reservoir” where it states the area is “strewn with large blocks” of the lustrous, black “garnet/gedrite rock” – described as very coarse grained, with maximum crystals 5 to 10 cm.  The area is strewn with broken down small outcrops and loose blocks of several kinds but eventually a dark rock with large reddish almandine (based on other EDS analyses) sticking through the moss and lichen-covered surface was located and sampled (full view photo - 8 x 7.5 x 3 cm).  Right near the block was a small quartz rich boulder with similar large amphibole crystals, which was also sampled (close-up photo – FOV 13 cm).

As indicated by the results from both samples, the average (red dot) of multiple subsamples of each is just barely in the anthophyllite compositional range, potentially rendering Lundgren’s 1979 identifications obsolete.  The subsample data of sample 1017 trends into the adjacent gedrite and ferro-anthophyllite ranges, while 1019 trends into the gedrite range.  Both just skirt the ferro-gedrite range.  These crystals are essentially 4-way fence-sitters!  Whether any of Lundgren’s “gedrite” crystals from the area are confirmed awaits further collecting and analyses. ​

Samples 759, 1575 and 3590 (left to right, top to bottom):  These are 3 sample of various habits of “tremolite” that are typical of the marble belt of western Connecticut, underlain by the Cambro-Ordovician Stockbridge/Inwood Marble.  Based on their white to very pale lime green color, and historical information, there was little doubt that they are tremolite, one of the few amphiboles that can be reliably sight-identified.  The goal was to confirm their identification with the same level of data quality as the other amphibole samples and to see if the composition varied along with the habit.

the 26 mm crystal in the photograph.
Sample 3590 is from a typical splintery radiating crystal aggregate (8.5 x 5.5 x 5.5 cm) from Pfizer Quarry, Canaan village, North Canaan.  This is also a very common tremolite habit in the marble belt, most of it occurs this way.
As expected, the TEM-EDS results confirmed the tremolite identification for all 3 samples.

Actinolite:        {Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Pyrophyllite:    Al2Si4O10(OH)2
Talc:                 Mg3Si4O10(OH)2
Anthophyllite: {Mg2}{Mg5}(Si8O22)(OH)2

This ambiguity needed to be clarified.  It seemed to me the whole package of visual and physical properties are most like the pyrophyllite deposits in North Carolina and Graves Mountain, Georgia.

​Initially an SEM-EDS analysis was conducted courtesy of Micromounters New England with some ambiguous results.  It did show, surprisingly, that it is definitely not pyrophyllite, there is no aluminum, and there is a lot of Mg present.  It is some kind of Mg-Fe silicate, with the Smart Quant report indicating it is magnesium-dominant with a Mg/(Mg+Fe) ratio of 0.77.  Based on the initial analytical results, it is possibly ferroan anthophyllite (Mg>Fe) or ferroan cummingtonite (Mg>Fe); or one of the similar but rarer non-aluminous amphiboles.  However, given its softness, it could be talc.  Clearly the limitations of SEM-EDS were reached on this mineral and that another type of analysis was necessary.

Therefore, optical microscopy, selected area electron diffraction (SAED) zone patterns and TEM-EDS analyses were conducted in 2016.  Collectively, they show the material is essentially fibrous talc containing/contaminated with fibrous anthophyllite with a little Fe impurity.  Note the similarity of the EDS spectra, but the SAED zone patterns show the difference in crystal structure.  No wonder this was a tough nut to crack!  Those results are shown below:

​Sample 3440:  A nice piece of “mountain leather” (11 x 5.5 x 2 cm) that formed sandwiched between 2 layers of calcite “dogtooth” habit crystals (note abundant “toothmarks”), found at the Agstone Quarry, Danbury and labeled “palygorskite” by Ronald Januzzi.  “Mountain leather” is a field term for uncharacterized mats or masses of finely fibrous mineralization that could be tremolite, but could also be palygorskite, (Mg,Al)2Si4O10(OH)·4H2O or more likely sepiolite, Mg4Si6O15(OH)2 · 6H2O.  The latter 2 minerals are not amphiboles, but have similar chemistry aside from the Al in palygorskite.  The TEM-EDS results did not detect Al and are a match for sepiolite.

Jacqueline Giblin & Melissa Luna (2016 GSC Grant Awardees)
Faculty Sponsor: Michael Wizevich
GSC Newsletter Article Project Summary

​The purpose of this project was to utilize uranium-lead (U-Pb) dating of detrital zircon grains to determine the provenance of the sediment infill of the Mesozoic Hartford and Pomperaug basins. The source areas for much of the sedimentary fill of the Hartford and Pomperaug rift basins is not well constrained due to discontinuous outcrop, complex paleocurrent patterns and complicated tectonic history of the source areas. Scientists have proposed sources from the east, west, and both the east and west; there is little agreement on a definitive source or sources of material in the basin. Zircon is a durable mineral found in nearly all sedimentary rocks and can be dated by Laser Ablation Inductively Coupled Plasma Mass Spectrometer (LA-ICPMS) analysis of U-Pb in the detrital zircon grains.  The age of a detrital zircon provides the date of the source rock in which it formed. Dates of zircons and potential source rocks can be matched and thus provide the areas that they came from. 

Figure 1: Map of Hartford and Pomperaug basins contain sample locations (stars) and paleocurrent data from Hubert et al. (1992).

rock crusher, sieved to separate the grains between​To get a broad representation of the basin fill within the Hartford basin, samples were taken from the Triassic New Haven Arkose (NH-15-1; SE basin- North Haven and NH-15-1; NW basin- Simsbury), the Jurassic East Berlin Fm (EB-15-2; center basin- Berlin), and the Jurassic Portland Fm (P-15-1; NE basin- Manchester and P-15-2; SE basin- Durham). Two samples of the Triassic South Britain Fm (SBF-2; Pierce Hollow and SBF-4; Rattlesnake Members) were collected in the SW Pomperaug basin (Figure 1). The samples were pulverized with a hydraulic  63 and 500mm in diameter,

treated to remove iron coatings from the grains, and then density separated using lithium metatungstate and diiodomethane heavy liquids in separatory funnels. The dense minerals were tapped off, rinsed, dried and magnetically separated using a Frantz magnetic separator.  ​
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Zircons were then handpicked from the non-magnetic portion of the sample.  Approximately 100 zircon grains were picked per sample and sent to the LaserChron Center (University of Arizona) for U-Pb age-dating on a LA-ICPMS. Several samples were “double dated,” where age-dates were taken on the core and rims of the same zircon. SEM cathodoluminescence (CL) was utilized to distinguish rims and cores of the zircon (Figure 2).

​The funding provided by GSC enabled us to analyze two samples at the University of Arizona LaserChron Center, which contributed to the wide representation of locations throughout the basins. The dates of this study provide a new data set and perspective to the ever complex and debated provenance of the CT Mesozoic basins. 

Figure 3: Cathodoluminescence (CL) images of typical Mesozoic detrital zircons.  

By Harold (Fritz) Moritz

During the winter of 2009-2010 a Home Depot store was constructed at a site on state Route 111 in northern Trumbull (aka Long Hill).  This site initially saw some grading and rock removal in the 1990s for a planned retail outlet known as Old Mine Plaza in allusion to the adjacent Old Mine Park.  However, no construction was ever done and it sat idle until the Home Depot construction. 

With its proximity to Old Mine Park, a place famous for its topaz and fluorite-rich hydrothermal veins and amphibolite-hosted scheelite and ferberite pseudomorphs thereof, the defunct plaza and the new Home Depot construction were a magnet for mineral collecting.  The bedrock is mostly amphibolite, with some marble, mapped as the Silurian basal member of the Silurian-Devonian The Straits Schist, which are locally very well exposed.  There was generally little overburden of Pleistocene age on the site. 
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However, during the Home Depot construction a large, underground storm water storage gallery was constructed by blasting a chamber into the bedrock.  This was presumably done because of the limited land available for a surface retention basin, so it was placed under the parking lot by filling the space with nested, hollow concrete structures that could support the overlying parking (see Figure 1).  The walls of the gallery exposed mostly amphibolite bedrock, but the southeast corner revealed a layer of overlying glacial till.

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Fig 1. Underground storm water retention basin under construction in January 2010.  The walls exposed mostly amphibolite bedrock, but glacial till was exposed in the corner at far left (Harold Moritz photo).

I found this small till outcrop (see Figure 2) interesting because it provided a relatively rare, fresh cross-section of what appears to be the lower till.  Although lower till may be volumetrically more abundant than the upper till because it cores drumlins and other areas of thick till (see Melvin and others, 1992 and Stone and others, 2005), the upper till almost completely blankets the lower till from view.  If there was any upper till at this site it was stripped away by site grading.  Because glacial till in general does not have much economic value there are few excavation pits were it was mined for anything other than “clean fill” on a small temporary scale. ​
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Fig. 2:  Exposure of what appears to be lower till in the wall of the retention basin.  Note the fine-grained, deformed matrix and tightly packed cobbles and boulders.  Some of the boulders may look competent, but some could be readily crumbled by scraping with the hammer shown for scale (Harold Moritz photo).

​These pits tend to expose only the surficial upper till, which is generally sandier and loose compared to the lower till and will not hold up stable walls.  It apparently formed from ablation on top of melting ice rather than under it.  Lower till tends to be clay-rich and so compact that it can be difficult to excavate or drill through.  At a large construction site in Cromwell, along state Route 372, between I-91 and state Route 3, an excavator was used to cut into a lower till exposure. It carved a wall that was actually past vertical, with prominent bucket teeth marks.  At a site along I-95 in Branford I worked at a site underlain by arkosic conglomerate where an excavator apparently refused on this rock, as did screw augers.  However, subsequent drilling with a tri-cone rotary bit and water circulation passed through 10s of feet of this “bedrock” before refusing on the real bedrock.  What I thought was shallow bedrock was actually dense lower till that had the same red-brown color (common in till overlying the Mesozoic sedimentary rocks) as the underlying conglomerate.  Lower till at the ConnDOT facility on state Route 3 in Rocky Hill, next to Dinosaur State Park, is similarly so dense that it could only be drilled with difficulty.

Lower till lies directly on bedrock and given its compact nature was almost certainly formed under continental scale ice sheets and may have been overridden by multiple ice advances.  Thus it could date back to the beginning of the Pleistocene 2.59 Ma and display evidence of deformation in the finer-grained matrix and decomposition of larger clasts.  Such is the case at the Trumbull exposure.
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The matrix at Trumbull is pale gray, very compact, unconsolidated silt and clay.  But boulders and cobbles make up around half of the exposure.  They are very tightly packed into the matrix and may be framework supported as they are almost touching in many areas and nearly fit together like a mortared stone wall.   The matrix shows evidence of deformation from compaction, but also shows orange-rusty staining along fractures closer to the surface.  The cobbles and boulders consist mostly of light colored to rusty schistose rocks, with only a few white marble and dark amphibolite rocks present despite their proximity.  Interestingly, many of the schistose boulders were nearly completely decomposed, their feldspars altered to clays, and could be crumbled by simply scraping them with the small rock hammer shown.  They were obviously very competent when emplaced but enough time has passed to allow in-situ weathering similar to the formation of saprolitic soil from bedrock, but in this case only within specific clasts.  I’ve encountered similarly decomposed boulders in drill samples from lower till in Bantam, but never in upper till.  Could this process have happened during only the latest glaciation of the past 100,000 years, or is it evidence that this till is from a much older Pleistocene glaciation?  

References
Melvin, R. L.; Stone, B. D.; Stone, J. R.; & Trask, N. J. (1992), Hydrogeology of thick till deposits in Connecticut. U. S. Geological Survey open-File Report 92-43.

Stone, J. R.; Schafer, J.; London, E. H.; DiGiacomo-Cohen, M. L.; Lewis, R. S.; & Thompson, W. (2005), Quaternary Geologic Map   of Connecticut and Long Island Sound Basin. USGS Scientific Investigations Map 2784.