Howlite Mineral Data

General Howlite Information

Chemical Formula:

Ca2B5SiO9(OH)5

Composition:

Molecular Weight = 391.32 gm

Calcium 20.48 % Ca 28.66 % CaO

Silicon 7.18 % Si 15.35 % SiO₂

Boron 13.81 % B 44.48 % B₂O₃

Hydrogen 1.29 % H 11.51 % H₂O

Oxygen 57.24 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₂B₅SiO₉(OH)₅

Environment:

Secondary mineral in arid environments.

IMA Status:

Valid Species (Pre-IMA) 1868

Locality:

Tick Canyon, Los Angeles Co., California. Link to MinDat.org Location Data.

Name Origin:

Named after Henry How of Nova Scotia when he first described it in 1868.

Name Pronunciation:

Howlite

Synonym:

ICSD 15178

PDF 26-1404

Howlite Image

Images:

Howlite

Comments: Silky nodule of howlite.
Location: Windsor, Nova Scotia, Canada. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Howlite Crystallography

Axial Ratios:

a:b:c =1.3697:1:0.9217

Cell Dimensions:

a = 12.78, b = 9.33, c = 8.6, Z = 4; beta = 104.83° V = 991.28 Den(Calc)= 2.62

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/c

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 6.207(1), 3.894(0.95), 3.094(0.65),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
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S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
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Finney J J , Kumbasar I , Konnert J A , Clark J R , American Mineralogist , 55 (1970) p.716-728, Crystal structure of the calcium silicoborate, howlite

View Additional jPOWD Structure files for Howlite
[1]

Physical Properties of Howlite

Cleavage:

None

Color:

Colorless, White.

Density:

2.58

Diaphaneity:

Translucent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Nodular - Tuberose forms having irregular protuberances over the surface.

Hardness:

2.5-3.5 - Finger Nail-Copper Penny

Luminescence:

Fluorescent, Long UV=bright sky blue.

Luster:

Earthy (Dull)

Magnetism:

Nonmagnetic

Streak:

white

Optical Properties of Howlite

Gladstone-Dale:

CI meas= -0.008 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.007 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2252,KPDmeas= 0.2287,KC= 0.2269
Ncalc = 1.59

Optical Data:

Biaxial (-), a=1.58, b=1.59, g=1.6, bire=0.0200, 2V(Calc)=88, 2V(Meas)=60-90. Dispersion none.

Pleochroism (x):

none.

Pleochroism (y):

none.

Pleochroism (z):

none.

Calculated Properties of Howlite

Electron Density:

Bulk Density (Electron Density)=2.62 gm/cc
note: Specific Gravity of Howlite =2.62 gm/cc.

Fermion Index:

Fermion Index = 0.03
Boson Index = 0.97

Photoelectric:

PE_Howlite= 2.97 barns/electron
U=PE_Howlite x rElectron Density= 7.79 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Howlite is Not Radioactive

Howlite Classification

Dana Class:

25.03.05.01 (25)Anhydrous Borates Containing Hydroxyl or Halogen

(25.03)Dana Type

(25.03.05)Dana Group

25.03.05.01 Howlite Ca2B5SiO9(OH)5 P 2₁/c 2/m

Strunz Class:

06.CB.20 06 - BORATES

06.C - Triborates

06.CB -Ino-triborates

06.CB.20 Howlite Ca2B5SiO9(OH)5 P 2₁/c 2/m

Other Howlite Information

References:

NAME( MinRec) PHYS. PROP.(Collectors Book of Fluorescent Minerals) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Howlite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - EUROmin Project
5 - Ecole des Mines de Paris
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (MinSocAm)
10 - Handbook of Mineralogy (UofA)
11 - MinDAT
12 - Mineral and Gemstone Kingdom
13 - Mineralienatlas (Deutsch)
14 - Online Mineral Museum
15 - QUT Mineral Atlas
16 - Ruff.Info
17 - Tradeshop.com - The Rainbow of Gems
18 - WWW-MINCRYST

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Ask about Howlite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Howlite Specimen Label here :

Howlite

Ca2B5SiO9(OH)5
Dana No: 25.03.05.01 Strunz No: 06.CB.20
Locality:

Notes: