Locality: Roadside boulder, Two Mile Rd., East Hanover, NH
Specimen Size: 11 cm specimen of massive diabase rock with embedded anorthite crystals.
Field Collected: Tom Mortimer
Catalog No.: 1775
Notes: Reference: Hitchcock, Geology of New Hampshire Vol. 3, pg 90, "Anorthite ... most notable specimens are found in the diabase at East Hanover (NH). There a rock occurs that is filled with crystals of this species...often an inch in length and breadth. The rock is so full of them that it is an anorthite porphyry."
This specimen is from that area of East Hanover.
A diabase is a volcanic basalt rock, a dark plutonic gabro, medium to fine textured.
Locality: Roadside boulder, Two Mile Rd., East Hanover, NH
Specimen Size: 14 cm specimen of massive diabase rock with embedded anorthite crystals.
Field Collected: Tom Mortimer
Catalog No.:
Notes:
Locality: Roadside boulder, Two Mile Rd., East Hanover, NH
Specimen Size: 1.5 cm longitudinal anorthite crystal section illustrating cleavage.
Field Collected: Tom Mortimer
Catalog No.: 1775
Notes:
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
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.
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.
Locality: West side of Piper Mtn., Gilford, NH
Specimen Size: fov 1 cm, blue-schiller zone of labradorite
Field Collected: Tom Mortimer - Sept, 2011
Catalog No.:
Notes: Specimen orientation to minimize blue schiller effect.
Locality: Pulpit Rd. (residential construction site) Bedford, NH
Specimen Size: Top: 2 mm anorthite crystal embedded in calcite. Bottom: 2 mm anorthite crystal with oxide dendrites
Field Collected: Tom Mortimer - June 2011
Catalog No.: u1609
Notes: I have had two EDS analyses on these crystals. The first EDS analysis by Kerry Day (a grain on carbon tape) and a second EDS analysis from Microvision Labs in Chelmsford, MA. (a polished grain analysis from a section of the crystal shown in this photo). It is gratifying to see the Al:Si:Ca ratios on the Day and Microvision plots to be nearly identical! I would note that two other anorthite analyses included within the anorthite gallery (TMortimer71 (raw grain - from documented anorthite locality) and TMortimer133 (polished grain) show a substantially stronger silicon response.
Meionite, Anorthite, Zoisite, and Clinozoisite all approximate the chemistry suggested by these plots, although anorthite has less Ca content than the other three.
Hardness testing (with a professional hardness point set) indicates a hardness of 6 to 7 (Hardness testing on small crystals under the scope can be a challenge.) Meionite has a hardness of 5-6, Anorthite 6 to 6.5, Zoisite 6-7 and clinozoisite of 7.
Fred Pough's Field Guide to Rocks and Minerals indicates that meionite, zoisite, and clinozoisite are all readily fusible. Heating crystal grains from this specimen to glowing red with my propane torch gave no indication of melting. I must therefore conclude that these small crystals are anorthite.
Raman spectroscopy or XRD could further support the ID of these crystals. Fortunately I have quite a few.
Small, pale-green, diopside crystals are associated with these milky anorthite crystals.