Cavansite on Stilbite

Object/Artifact

-

Crater Rock Museum

Cavansite

Cavansite

Name/Title

Cavansite on Stilbite

Entry/Object ID

2004.1.4

Description

Chemical Composition: Ca(V^4+O)Si4O10*4H2O Crystal System: Orthorhombic System Description: Common Name: Cavansite with Stilbite crystals on the matrix Group Name: Zeolite Chemistry: Ca(VO)Si4O10(H2O)4, Hydrated Calcium Vanadium Silicate. Chemistry: NaCa2Al5Si13O36 -14H2O, Hydrated sodium calcium aluminum silicate Class: Silicates Subclass: Phyllosilicates / Tektosilicates Associated Minerals: Zeolite Families Found at Wagholi, Pune District, Maharashtra, India. This specimen has beautiful deep blue cavansite crystals on white crystal of stilbite on the matrix Estimated Value: $20,000 PHYSICAL CHARACTERISTICS: for both Cavansite & Stilbite Color: Cavansite =greenish-blue to ocean blue / Stilbite =pink or white: also tinted yellow and red Luster: Bothe are vitreous to pearly but stilbite has a prominant pinacoid & cleavage surface . Transparency: For both the crystal are transparent to translucent. Crystal System: Cavansite is orthorhombic / Stilbite is monoclinic (2/m) Crystal Habits: Cavansite radiating acicular crystals forming spherical crystal clusters. Stilbite include platy often thin crystals that can aggregate together into a wheat sheaflike structure. The prominant pinacoid is sometimes but rarely modified by other pinacoid and prism faces. Cruciform (cross-like) twins can also be found. Also forms radiating nodules. Cleavage: Both are perfect in one direction but Stilbite is parallel to the prominant pinacoid. Fracture: Cavansite is conchoidal / Stilbite is uneven Hardness: 3 - 4 & 3.5 -4 Specific Gravity is approximately 2.33 & 2.2 Streak: Cavansite is blue & Stilbite is white Associated Minerals include zeolites such as stilbite and heulandite as well as calcite, apophyllite , babingtoniteand quartz. Other Characteristics: larger crystals show an unusual internal reflection. Notable Occurrence: For cavansite Poona, India and Columbia Co. and Malheur Co., Oregon, USA. and for stilbite Poona, India; Scotland; Iceland; New Jersey and Nova Scotia, Canada. Best Field Indicators: For cavansite are color, associations, locality and crystal habit , stilbite are crystal habit, luster, density and associations. Fracture: Conchoidal - uneven Hardness: 3 Calcite Luster: Pearly Occurrence: Occurs in cavities in basalts and tuffs, usually in association with zeolites and is known e.g. from Poona, India. Stilbite commonly forms nice crystals inside the petrified bubbles (called vesicles) of volcanic rocks that have undergone a small amount of metamorphism. Also occurrence include ore veins, late pegmatite stages, seams in granite and there are numerous other localities for stilbite. Rock Color: Medium Rock Origin: Post-depositional Rock Type: Sedimentary Specific Gravity: 3 - 4 Streak: blue & white Texture: Cystalline Variety: -Cavansite is a beautiful and rare mineral. It was only discovered in the last 30 years and is found in only a few locallities. By far the best crystals come from the famous zeolite quarries in Poona, India. Crystal aggregates consist of spherical rosettes with jutting pointed crystals. The deep blue color of even the smallest cavansite crystals is truly amazing. A beautiful blue cavansite rosette perched on top of the muted colors of the typical zeolites makes a dramatic crystal association. Cavansite's rarity and beauty explain its recent popularity. -Stilbite is a common and perhaps the most popular zeolite mineral for collectors. Stilbite crystals can aggregate together to form a structure resembling wheat sheafs. This hourglass structure looks like several crystals stacked parallel to each other with the tops and bottoms of this structure fanning out while the middle remains thin. Stilbite's hallmark crystal habit is unique to stilbite and a rarer but related zeolite called stellerite. Whether in the wheat sheafs or not, stilbite can be a handsome specimen with its pearly luster and often colorful pink tints. Stilbite's structure has a typical zeolite openness about it that allows large ions and molecules to reside and actually move around inside the overall framework. The structure contains open channels that allow water and large ions to travel into and out of the crystal structure. The size of these channels controls the size of the molecules or ions and therefore a zeolite like stilbite can act as a chemical sieve. Stilbite's structure contains rings of alumino-silicate tetrahedrons oriented in one direction and this produces the prominent pinacoid faces, the perfect cleavage and the unique luster on those faces.

Collection

Suomynona Mineral Collection, Suomynona Collection

Acquisition

Accession

2004.1

Source or Donor

Suomynona Mineral Collection

Acquisition Method

Donation

Dimensions

Width

5 in

Depth

4 in

Length

9 in

Weight

4.39 oz

Dimension Notes

Dimension taken at widest points

Location

Location

Display Case

FS-16

Room

Frieda Smith Hall

Building

Crater Rock Museum

Category

Permanent

Moved By

Curtis Gardner

Date

May 25, 2023

Notes

Added current location