Locality: Hurricane Mtn., Conway, NH
Specimen Size: 12 mm field of view
Field Collected: Tom Mortimer
Catalog No.: 576
Notes: I have wondered for many years if these black hair specimens (I collected many) are arfvedsonite, riebeckite, or perhaps aegirine. All are possibilities from the Hurricane Mtn. locality. A qualitative EDS analysis did not resolve the ambiguity (the sodium response of EDS detector is low and not indicative of the true sodium proportion). Both arfvedsonite and riebeckite have a Fe:Si ratio of 5:8. Aegrine is lower, 4:8 (1:2). The plot appears to support a 5:8 ratio.
A review of two articles in volume 34 of the Canadian Mineralogist indicates this fibrous amphibole is riebeckite:
http://rruff.info/doclib/cm/vol34/CM34_1011.pdf by Foord et. al.: "The fine-grained riebeckite is a product of final low-temperature hydrothermal solutions that were present in the miarolitic cavities."
and
http://rruff.info/doclib/cm/vol34/CM34_1015.pdf by Hawthorne et. al. "fibrous Li-poor riebeckite partly fills some of the miarolitic cavities"
A 16 image stack processed with Helicon Focus.
Locality: Hurricane Mtn., Conway, NH
Specimen Size: 7 cm specimen with large zone of blue riebeckite var crocidolite.
Field Collected: Tom Mortimer (1982)
Catalog No.: 178
Notes:
Locality: Hurricane Mtn., Conway, NH
Specimen Size: 4 cm specimen with zone of blue riebeckite var crocidolite.
Field Collected: Tom Mortimer (1982)
Catalog No.:
Notes:
Locality: Hurricane Mtn., Conway, NH
Specimen Size: 2.2 cm specimen with acicular black hairs of riebeckite
Field Collected: Tom Mortimer (1982)
Catalog No.:
Notes:
Locality: North Moat Mtn., Bartlett, NH
Specimen Size: 2 cm mass of fibrous riebeckite
Field Collected: Gene Bearss (1985)
Catalog No.: A Gene Bearss collection specimen
Notes: Identification by Gene Bearss.
Locality: Hurricane Mtn., Conway, NH
Specimen Size: 1.6 cm terminated crystal, front and back views
Field Collected: Unknown - A purchased specimen - 8/15
Catalog No.: 1964
Notes: When purchased, this TN specimen was labeled as arfvedsonite. However the scratched surface is pale blue (visible, second photo), suggesting riebeckite.
An XRD analysis - arfvedsonite correlation had a slightly better correlation with arfvedsonite than with riebeckite XRD analysis - riebeckite correlation . This suggests an arfvedsonite crystal altering to riebeckite.
Locality: Hurricane Mtn., Conway, NH
Specimen Size: 2.2 cm field of view
Field Collected: Leroy Grant -1970's
Catalog No.: u2371
Notes: Mat of blue crocidolite on smoky quartz crystal with astrophyllite..