|
|
 |
|||||||||||||||||
|
|||||||||||||||||
 |
|||||||||||||||||
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Tregears, Little Treviscoe, St. Austell, Cornwall, United Kingdom
48 St. Lulitta, Bodmin, Cornwall, United Kingdom
7 Tregonning Park, St. Keverne, Helston, Cornwall, United Kingdom
Stevensite has been found at Dean Quarry. The Lizard, Cornwall, associated intimately with the disordered, hydrated variety of talc known as kerolite. Both minerals occur as pseudomorphs after pectolite and as microcrystalline anhedral masses filling cavities and veins in gabbro. Associated minerals include calcite and prehnite. The XRD data show that stevensite occurs as a physical mixture with kerolite, rather than as mixed-layer stevensite-kerolite. Kerolite is unaffected by glycerol treatment whilst stevensite readily expands: this test provides the only reliable distinction between the two minerals. Differences in IR and chemical data for stevensite and kerolite are subtle; data are broadly similar to those in the literature. Both minerals are readily decomposed to amorphous silica by hot concentrated HCl. Stevensite dehydroxylated at 400 degrees C for 1.5 h is virtually indistinguishable from kerolite. The Dean Quarry occurrence is similar to many others worldwide. Stevensite and kerolite formed after prehnite, calcite, analcime, pectolite and natrolite during a phase of decomposition and alteration of these earlier minerals. "Stevensite" from the first British occurrence in the Whin Sill, North Tyne, has been re-examined and appears to be kerolite or "hydrated-talc".
This record provided courtesy of AGI/GeoRef.
This article has been cited by other articles:
|
|
 |
|
  J. Cuadros, V. M. Dekov, and S. Fiore Crystal chemistry of the mixed-layer sequence talc-talc-smectite-smectite from submarine hydrothermal vents American Mineralogist, August 1, 2008; 93(8-9): 1338 - 1348. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. YENIYOL Characterization of a Mg-rich and low-charge saponite from the Neogene lacustrine basin of Eskisehir, Turkey Clay Minerals, December 1, 2007; 42(4): 541 - 548. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Cheshire and N. Guven CONVERSION OF CHRYSOTILE TO A MAGNESIAN SMECTITE Clays and Clay Minerals, April 1, 2005; 53(2): 155 - 161. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. D'ORAZIO, C. BOSCHI, and D. BRUNELLI Talc-rich hydrothermal rocks from the St. Paul and Conrad fracture zones in the Atlantic Ocean European Journal of Mineralogy, February 1, 2004; 16(1): 73 - 83. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Cuevas, J. Cuevas, R. V. de la Villa, S. Ramirez, S. Petit, A. Meunier, and S. Leguey CHEMISTRY OF Mg SMECTITES IN LACUSTRINE SEDIMENTS FROM THE VICALVARO SEPIOLITE DEPOSIT, MADRID NEOGENE BASIN (SPAIN) Clays and Clay Minerals, August 1, 2003; 51(4): 457 - 472. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. J. Levelle, R. J. Leveille, F. J. Longstaffe, and W. S. Fyfe KEROLITE IN CARBONATE-RICH SPELEOTHEMS AND MICROBIAL DEPOSITS FROM BASALTIC CAVES, KAUAI, HAWAII Clays and Clay Minerals, August 1, 2002; 50(4): 514 - 524. [Abstract] [Full Text] [PDF]
|
|
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
