| This page is an alphabetical photo gallery of minerals from the Ellacoya Locality, Gilford, New Hampshire. (A locality specific photo set from mindatnh.org) 22 species, 49 mineral photos: See also: Mindat.org locality link The Ellacoya locality is a pile of boulders blasted from the widening of Rt. 11 in Gilford, NH. It is located on the eastern side of the Belknap Mountains, across from the entrance to the Ellacoya state park. GPS: 43 deg 34 min. 21.49 sec. N 71 deg 21 min. 22.41 sec. W. The coordinates given by mindat.org are way off. This is believed to be an "open" site, however I [tm] have not visited this site in the last decade. The paper bound book Stepping Stones across New Hampshire by Long & Roberts (Amazon $19.95, 2020) provides an excellent, well illustrated, tutorial on the geologic history and structure of the Belknap Mountains, the host rock body for the Ellacoya locality. | |
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Locality: Ellacoya Locality Notes: Google Earth view. Rt. 11 at bottom. |
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Locality: 2004 site photo Notes: |
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Species: ACTINOLITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.2 mm field of view Field Collected: Tom Mortimer Catalog No.: u2256 Notes: A polished grain EDS analysis (BC357) indicated actinolite. The APFU calculated from this analysis is Ca2(Mg2.1,Fe1.77,Al0.22)Si7.7O16.2 normalized for 2 Ca. The trace of neon is a bogie. From analysis Mg/(Mg+Fe) = 0.55. This ratio must be less than 0.5 for ferroactinolite. So this is close to ferroactinolite. |
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Species: ACTINOLITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 3.5 mm field of view. Actinolite blades on feldspar. Field Collected: Tom Mortimer Catalog No.: NC Notes: |
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Species: ACTINOLITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.8 mm field of view. Stubby actinolite crystals in diorite vug. Field Collected: Tom Mortimer Catalog No.: Notes: |
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Species: ACTINOLITE var. Byssolite Locality: Ellacoya Locale, Gilford, NH Specimen Size: 14 mm field of view. Field Collected: Tom Mortimer Catalog No.: u2372 Notes: Byssolite is a fibrous to hair-like crystal or mass of fibers frequently in the actinolite-tremolite series, but may be any amphibole species. |
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Species: ACTINOLITE - TREMOLITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.3 mm field of view. White end of crystals suggests zoning to tremolite. Field Collected: Tom Mortimer Catalog No.: Notes: |
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Species: ALBITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 14 mm field of view – box-work crystal group Field Collected: Tom Mortimer Catalog No.: NC Notes: |
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Species: AUGITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 3 mm black augite crystal with Titanite, (orange) Field Collected: Tom Mortimer Catalog No.: u869 Notes: EDS analysis indicates these black prisms are augite. |
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Species: AUGITE Locality: Lockes Hill, Gilford, NH Specimen Size: 1.2 cm augite crystal weathered from diorite matrix Field Collected: Tom Mortimer Catalog No.: 1481 Notes: |
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Species: CHABAZITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 10 mm cluster of milky, rhombic, chabazite crystals. Largest is 4 mm. Field Collected: Tom Mortimer Catalog No.: u1131 Notes: Rhombic shape and luster of these crystals is characteristic of chabazite. EDS analysis of similar crystals from the Ellacoya locale indicates the species is chabazite: (Ca,K2,Na2)2[Al2Si4O12]2 · 12H2O |
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Species: CHABAZITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: Largest crystal is 1.4 mm. Field Collected: Tom Mortimer Catalog No.: Notes: |
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Species: HYDROXYLAPATITE - APATITE-(CaOH) Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.2 mm clear apatite crystal with internal reflections Field Collected: Tom Mortimer Catalog No.: u606 Notes: A polished grain EDS analysis indicated the hydroxylapatite species. No fluorine was detected by detector with good light element sensitivity down to carbon. The large peak in the plot at 277 eV is due to the carbon coating of the specimen block. The Ellacoya apatite photo on mindat.org (by Scott Whittemore ) is labeled as Fluorapatite. A March 2005 EDS analysis of a clear Ellacoya apatite was done by Jim Nizamoff while at UNO, but the instrument used had no response below about 1.0 KeV, where fluorine, if present, would have registered. |
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Species: CLINOCHLORE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 2.7 mm field of view. Field Collected: Tom Mortimer Catalog No.: NC Notes: Chlorite Group – Clinochlore – visual ID |
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Species: FLUORITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 2.7 mm field of view. Field Collected: Tom Mortimer Catalog No.: u629 Notes: Fluorite is uncommon at the Ellacoya locality |
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Species: ORTHOCLASE var. Adularia Locality: Ellacoya Locale, Gilford, NH Specimen Size: 2.7 mm field of view. Field Collected: Tom Mortimer Catalog No.: e.g. u703 Notes: EDS analysis has shown these to be a potassium feldspar. Orthoclase assumed. |
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Species: ORTHOCLASE var. Adularia Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.2 mm field of view. Field Collected: Tom Mortimer Catalog No.: e.g. u703 Notes: EDS analysis has shown these to be a potassium feldspar. Orthoclase assumed. |
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Species: MAGNETITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.1 mm octahedron, two views Field Collected: Tom Mortimer Catalog No.: u613 Notes: |
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Species: MICROCLINE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 6 mm crystal Field Collected: Tom Mortimer Catalog No.: Notes: Drawing illustrates twinning. |
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Species: MOLYBDENITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 2 mm field of view Field Collected: Tom Mortimer Catalog No.: u607 Notes: |
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Species: OPAL var. Hyalite Locality: Ellacoya Locale, Gilford, NH Specimen Size: 3.5 cm field of view Field Collected: Tom Mortimer Catalog No.: u502 Notes: Daylight and SW UV views |
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Species: OPAL var. Hyalite Locality: Ellacoya Locale, Gilford, NH Specimen Size: Opal on tip of quartz crystal, 1.1 mm globule Field Collected: Tom Mortimer Catalog No.: Notes: Downward pointing quartz crystal. Gravity induced silica drip. |
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Species: PYRITE - altering to goethite Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.4 mm crystal (pyritohedron - pentagonal dodecahedron) Field Collected: Tom Mortimer Catalog No.: Notes: |
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Species: QUARTZ with Microcline Locality: Ellacoya Locale, Gilford, NH Specimen Size: 4 cm field of view. Portion of 5 inch mairolitic cavity in granite Field Collected: Tom Mortimer Catalog No.: Notes: |
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Species: QUARTZ Locality: Ellacoya Locale, Gilford, NH Specimen Size: 10 mm Tessin habit crystal Field Collected: Tom Mortimer Catalog No.: Notes: |
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Species: QUARTZ Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.8 cm Tessin habit crystal Field Collected: Tom Mortimer Catalog No.: Notes: |
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Species: PHLOGOPITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: Foreground mica crystal is 0.7 mm Field Collected: Tom Mortimer Catalog No.: u2173 Notes: This could be one of several dark mica species, but the nice hexagonal form initially suggested annite to me. An April 2018 carbon tape mounted grain EDS analysis (set 19, BC289) indicated a potassium, magnesium dominant (over iron) mica, so this is phlogopite. The chemistry from the analysis gave: (normalized for one atom of potassium) K(Mg1.6,Fe1.3)Al1.3Si3.6O21.1Cl0.1. This is not too far from the phlogopite - annite midpoint. This is a reasonably satisfying analysis. For a phlogopite - annite mica, the Mg + Fe should add to 3, the Al should be 1 and the Si should be 3 Some greenish foliated balls of mica are also seen at this locality. These are likely a chlorite group species. The chlorite group micas do not have potassium. |
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Species: PHLOGOPITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 4 mm field of view Field Collected: Tom Mortimer Catalog No.: u2170 Notes: |
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Species: TITANITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 2 mm titanite crystal Field Collected: Tom Mortimer Catalog No.: u618 Notes: |
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Species: TITANITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.4 mm titanite crystal Field Collected: Tom Mortimer Catalog No.: u609 Notes: |
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Species: TITANITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.7 mm titanite crystal Field Collected: Tom Mortimer Catalog No.: u530 Notes: |
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Species: TITANITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 2 mm titanite crystal Field Collected: Tom Mortimer Catalog No.: u623 Notes: |
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Species: TITANITE Locality: Ellacoya Locale, Gilford, NH Specimen Size: 9 mm titanite crystal Field Collected: Tom Mortimer Catalog No.: 1410 Notes: I believe this is the largest titanite crystal that has been found to date at the Ellacoya locale. |
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Species: UNDETERMINED Locality: Ellacoya Locale, Gilford, NH Specimen Size: zoned, prismatic crystals. Maximum height is 0.01 m Field Collected: Tom Mortimer Catalog No.: Notes: |
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Species: UNDETERMINED Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.5 mm green amphibole crystal Field Collected: Tom Mortimer Catalog No.: u600 Notes: EDS analysis suggested the species ferri-tischermakite to analyst Kerry Day, based on the Fe > Ca in comparison to epidote EDS analysis. |
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Species: UNDETERMINED Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.0 mm field of view Field Collected: Tom Mortimer Catalog No.: u983 Notes: |
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Species: UNDETERMINED Locality: Ellacoya Locale, Gilford, NH Specimen Size: 0.5 mm crystal Field Collected: Tom Mortimer Catalog No.: u600 Notes: |
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Species: UNDETERMINED Locality: Ellacoya Locale, Gilford, NH Specimen Size: 1.4 mm field of view Field Collected: Tom Mortimer Catalog No.: u600 Notes: Insert is of a similar appearing peridot crystal, one of my original considerations for these green crystals. But, chemistry does not fit peridot-olivine. |
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Species: UNDETERMINED Locality: Ellacoya Locale, Gilford, NH Specimen Size: 0.6 mm field of view Field Collected: Tom Mortimer Catalog No.: u600 Notes: This mineral photos well, so lots of images! |
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Species: UNKNOWN Locality: Ellacoya Locale, Gilford, NH Specimen Size: Red-brown bipyramids. 1.5 mm field of view. Field Collected: Tom Mortimer Catalog No.: u631 Notes: May be just pyrite altered to goethite, but something like a pyrochlore group mineral is also a possibility. |
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Locality: Belknap Mts., NH |
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Species: ANORTHITE Locality: Piper-Whiteface Trail, west side Piper Mtn., Gilford, NH Specimen Size: 5 cm specimen. Anorthite crystals in diabase matrix Field Collected: Tom Mortimer (Oct., 2010) Catalog No.: Notes: Anorthite confirmed by EDS analysis |
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Species: ANORTHITE - Labradorite Locality: West side of Piper Mtn., Gilford, NH Specimen Size: 5 cm specimen with 8 mm blue-schiller zone of labradorite, top-middle-left Field Collected: Tom Mortimer - Sept, 2011 Catalog No.: 1804 Notes: This is the first nice blue schiller example of New Hampshire labradorite I have seen. Labradorite is a member of the plagioglase feldspar series. Labradorite contains 50 to 70 percent anorthite and 30 to 50 percent albite. The host rock is the Gilmantion (Augite) Monzodiorite. This labradorite fluoresces a deep red color in short wave UV. The glassy-milky labradorite zones are more intense. |
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Species: ANORTHITE - Labradorite Locality: West side of Piper Mtn., Gilford, NH Specimen Size: fov 1 cm, blue-schiller zone of labradorite. Zoom view of above specimen. Field Collected: Tom Mortimer - Sept, 2011 Catalog No.: 1804 Notes: Specimen orientation to maximize blue schiller effect. The blue schiller is very dependant on the angle of the incident light. |
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Species: FORSTERITE Locality: West side of Piper Mtn., Gilford, NH Specimen Size: 1 cm green, glassy, Forsterite bleb in Basalt Field Collected: Tom Mortimer - Sept, 2011 Catalog No.: 1458 Notes: Forsterite confirmed by EDS analysis |
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Species: MARIALITE - Scapolite group Locality: Lockes Hill, Gilford, NH Specimen Size: 3 cm specimen with white embedded prismatic marialite crystals Field Collected: Tom Mortimer Catalog No.: 1488 Notes: Marialite confirmed by EDS analysis. This was a polished grain analysis with a quantitative report. The chemistry indicated by this anlysis is: (Na2.35Ca1.52K0.23)Al3.95Si9O20.1Cl1.02 , normalized for 9 Si. Clearly a sodium dominant scapolite. |
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Species: SILLIMANITE - KYANITE polymorph Locality: Rt 11 road cut, near Minge Cove, Alton, NH Specimen Size: 8 cm specimen Field Collected: Tom Mortimer Catalog No.: u600 Notes: An aluminum silicate mineral was indicated by EDS analysis. Minerals with this chemistry include sillimanite, kyanite, and andalusite. The hardness tested as 7 to 7.5. This, combined with observed silky-fibrous texture in some areas suggests the species is sillimanite. However other zones within the two specimens collected are more bladed and blueish, suggesting kyanite. Deer, Howie & Zussman state in An Introduction to Rock Forming Minerals that "The polymorphic transition of kyanite to sillimanite appears to be sluggish and local persistance of kyanite in the sillimanite zone of metamorphism is not uncommon." The appearance of this crystal suggests that it was undergoing such a polymorphic transition. |
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Species: SYNCHESITE-(Ce) Locality: Rt. 11 storm drain excavation, near Lake Shore Park, Gilford, NH Specimen Size: 0.4 mm hexagonal, reddish, zoned, Synchysite-(Ce) Field Collected: Clayton Ford Catalog No.: u954 Notes: Clayton Ford had this specimen labeled as corundum. Synchysite-(ce) indicated by EDS analysis. |