Name/Title
Dravite / CleavelanditeEntry/Object ID
2009.62.64Description
Chemical Composition: see description
Crystal System: Orthorhombic System
Description: Common Name: Dravite / Cleavelandite
Chemistry: NaMg3(Al,Fe)6Si6O18(BO3)3(OH)4, complex Sodium Magnesium Iron Boro-Aluminium Silicate / NaAlSi3 O8, Sodium aluminum silicate.
Group: Tourmaline / K-Feldspar
Location: Paddar area, Kishtwar District (Jammu and Kashmir), India
Description: Large columnar black crystal with one end having white, small sheet like crystals and a small group of white crystals clumped together on one side of the column.
PHYSICAL CHARACTERISTICS OF DRAVITE:
Color is light brown to dark brown.
Crystal Habit is typically elongated three sided prisms. The terminations can be either a simple to complex trigonal pyramid or a flat basal face. The prism faces are striated lengthwise. In cross section, all tourmalines will appear predominantly triangular in shape with some crystals showing a hexagon. Doubly terminated crystals are hemimorphic meaning that the two ends of the crystal are not exactly alike. Massive forms can also be found.
Transparency: crystals are translucent to opaque.
Crystal System is Trigonal; 3m
Hardness is 7 - 7.5
Specific Gravity is 3.2+ (slightly heavier than average)
Cleavage is absent although there is basal parting.
Fracture is uneven to conchoidal.
Luster is vitreous.
Associated Minerals include those associated with metamorphic rocks such as micas, feldspars and quartz.
Other Characteristics: crystals are brittle and refractive indices = 1.62 and 1.68 .
Best Field Indicators are crystal habit, triangular cross-section, color and hardness
PHYSICAL CHARACTERISTICS OF CLEAVELANDITE:
Color is usually white (Albite is derived from the same root word as albino) or colorless but can be shades of blue, yellow, orange and brown.
Luster is vitreous to dull if weathered..
Transparency crystals are translucent to opaque and only sometimes transparent.
Crystal System is triclinic; bar 1
Crystal Habits include blocky, tabular and platy crystals. The typical crystal has a nearly rectangular or square cross-section with slightly slanted dome and pinacoid terminations. A variety called Cleavelandite forms very thin platy crystals that can grow rather large (15+ cm across) but can maintain an even thickness of only a few millimeters. Twinning is almost universal in albite. Crystals can be twinned according to the Albite, Carlsbad, Manebach and Baveno laws. Albite is a common constituent of granitic and syenite rocks. Can also be massive.
Cleavage is perfect in one and good in another direction forming nearly right angled prisms.
Fracture is conchoidal.
Hardness is 6 - 6.5.
Specific Gravity is approximately 2.61 (average)
Streak is white.
Associated Minerals are quartz, tourmaline and muscovite.
Other Characteristics: index of refraction is 1.53. Lamellar twinning may cause a grooved effect on cystal surfaces that appear as striations. Some albite may show an opalescence due to twinning and is referred to as moonstone.
Best Field Indicators are occurence, crystal habit, twinning, striations, density and index of refraction.
Fracture: conchoidal
Hardness: 3 Calcite
Luster: Vitreous
Occurrence: Platy albite, generally found in pegmatite.
Rock Type: Igneous
Specific Gravity: 2.2
Streak: white
Variety: Dravite is a little known species of the Tourmaline Group.
Cleavelandite is a variety of albite which is a k-feldsparCollection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Height
2 inWidth
2-3/4 inLength
6-1/2 inWeight
21.58 ozDimension Notes
Dimension taken at widest pointsLocation
Location
Display Case
DS-10Room
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentDate
May 10, 2023Notes
Added current location while cleaning shelf
