Mines and Decorative Stones
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Our approach and methodology for prepration of decorative stone Atlas of Iran

Introduction
Building and decorative stones are one of the most important natural resources of Iran. According to recent statistics, Iran has been listed among the fifht producers and consumer of building stones in the world.
One of the main reasons of unsuccessful supply of Iranian decorative stones in International markets is lack of precise information quality, quantity from these quarries. This Atlas has been prepared to overcome this problem. We mainly focused on introducing of important decorative stones based on ASTM criteria.

The following subjects have been taken into consideration in preparation of this Atlas:

a) Priorities Selecting Quarries:
The quarries have been selected based on available data from each of provinces and technical characteristics like minable reserves, current rate of exploitation, rock types, color, composition and quality.
The following minimum annual rates of production is used to categorize different quarries considered in this Atlas:

• Altered marbles and porcelain 10,000MT
• Travertine 5,000MT
• Marble 2,000MT
• Granite 3,000MT

b) Sampling:
Sampling has been carried out by groups of senior geologists. All attempts are made to take a representative samples from these quarries.

c) Reserve estimation:
One of the key factors in investment related decisions is assurance about the availability of mine reserves. For this purpose, recorded numbers in exploitation licenses were selected.

d) Evaluation of exploitation:
The real production rate can be limited due to geological constraints and involvement of unqualified people as managers. For example, in most cases, methodology for mine management applied does not meet minimum requirements of applicable global standards utilized in the mining section. Due to lack of management expertise and experience, even by having necessary exploitation equipment. they are unable to increase their production rates from minimum amount included in their original mining license.

e) Preparation of schematic sections:
Since, one of the main reasons of Atlas is to make possibilities for participation, cooperation and exploitation of foreign or local private sectors , so datas such as current and existing exploitation conditions, tectonic situation, morphology of materials which plays an important role in selection of the equipment has been gathered by use of a schematic sections .

f) Microscopic studies:
Since, the main and subsidiary minerals although is effecting a rock from points of colour and quality view,but also is a main determinant of applied consumption.
For example, the low oxide – mineral rocks have more constancy in color. Therefore the microscopic studies were necessary.

g) Lab selection and equipping:
In order to meet ASTM codes for physical and mechanical behaviour of quarry stones, we did our tests in laboratories of “The Construction Research Center”which would meet the needed standards .

h) Reliability of tests:
To meet ASTM standards, the confirmation of one international standard institute was necessary. The Industrial Research Institute of Iran has obtained all the required approvals for the equipments.

i) Mechanical tests:
All mechanical tests including sample preparation and methods of measurement were carried out as follows:

Sample preparation: Taken samples from the quarries have been cut in cutting workshops and sent to the laboratories for tests. ASTM standards are considered during sampling as shown in the following table.  

Quantity and size of samples based on ASTM standards

No.

Type of test

Number of samples

Size of samples (mm)

1

water absorption

Min. 3 samples, without layers

Rectangular cubic, with min. 51 and max. 75

2

specific density

Min. 6 samples with layers

Rectangular cubic, with min. 51 and max. 75

3

Compression test

5 samples for testing parallel and perpendicular to layer

Rectangular cubic, with min. 51 and max. 75

4

Module of elasticity

3 samples,without layers, perpendicular to layers 3 samples and 3 samples alongside of layer

Rectangular cubic, 102x204x57

5

grinding test

3 samples

Rectangular cubic, 26x51x51

6

bending test

3 samples

Rectangular cubic, 300x38x25


Based on standard codes, physical and mechanical tests should be done in each sample and mean value of tests should not be exceeding than 10%.
In addition to the prepared samples, we also prepared sample with the dimentions of 2×10×10 cm for presenting the polishing state so,the pictures of all the mines are based on their real sizes
.

Methodology of Preparation of Samples for lab tests
Samples Prepared from Quarries



Setting the Samples on the Pallet under Cutters



Cuting the Samples



Classification of the samples



Samples laging of each mine




Samples Coding & Packaging for dispaching to lab

Regarding the standard methodology for measurement of physical and mechanical specification , each sample should be tested in several times . The mean value of the tests if not distorted more than 10% , determined as the result . Other wise , the sample should be reprepared and repeating the tests .

j)
Methodology of Selecting Scientific name of Stones :
To prevent various names of stones which uses in different classifications , we determined the Dunhan System for notation of sedimentary stones and regarding the volcanic stones ,we cosidered the main and subsidiary materials and also the tissue of the stones .


Based on obtained results from these tests all decorative stones mentioned here, can be divided into four groups as follows:

Granite group:
Generally,and by definition granite is a volcanic rock, which consist of quartz and feldspar grains. Granite color varies from pink to gray with homogeneous texture. Usually, one or several mafic minerals associated with granite. In addition, some other volcanic rocks with mafic features dubbed as granite, however, lithologicaly they cannot be categorized as granite rocks.
Specification of granite decorative stone is shown in below table based on ASTMC615-96.

Physical & Mechanical spec.

quantity

Method of test

Maximum water absorption (wt.%)

0.4

ASTMC97-96

Minimum spg. (kg/m³)

2560

ASTMC97-96

Minimum compression (Mpa)

131

ASTMC170-90(Reapproved1994)

Module of elasticity(Mpa)

10.34

ASTMC99-87(Reapproved1993)

Min. grinding (hardness)

25

ASTMC241-90(Reapproved1997)

Min. bending stress (Mpa)

8.27

ASTMC880-96


Limestone group:
Limestone is sediment rock consisting of calcium carbonates (calcite minerals) or calcium-magnesium (dolomite) or both of these minerals. In the market of decorative stones, polishable re-crystallized limestones, dense microcrystalline limestones and travertine’s, are considered as a marble. Based on ASTM standard these rocks can be categorized as a limestone or marble.

According to ASTM standards, decorative limestones are classified based on their specific gravity into three groups:

1) Low density limestone – density between 1760 to 2160 kg/m³
2) Medium density limestone – density between 2160 to 2560 kg/m³
3) High density limestone – density more than 2560 kg/m³

Mechanical and physical specification of limestone is shown in below:

Physical & Mechanical spec.

quantity

Classified group

Method of test

Maximum water absorption (wt.%)

12

Low

ASTMC97

7.5

Medium

3

High

Minimum spg. (kg/m³)

1760

Low

ASTMC97

2160

Medium

2560

High

Minimum compression (Mpa)

12

Low

ASTMC170

28

Medium

55

High

Module of elasticity(Mpa)

2.9

Low

ASTMC99

3.4

Medium

6.9

High

Min. grinding (hardness)

10

All classes

ASTMC241


Marble group:
This group covers the wide range of rocks with different types of compositions and textures. Therefore, from the economical point of view, rocks with high content carbonate to low carbonates can be classified in this group. Most of the marbles have intermingled textures with quasi-crystalline minerals to 5mm grains. Onyx, as a transparent calcite, with various colors, belongs to this group. In addition, all dense and polished limestone can be supplied as a marble stone.

According to ASTM503-97, marble decorative and building stones are classified into four groups: Calcite, Dolomite, Serpentine and Travertine.
Mechanical and physical specification of marble stone is shown in below:

Physical & Mechanical spec.

quantity

Classified group

Method of test

Maximum water absorption (wt.%)

0.2

In all four groups

ASTMC97

Minimum spg. (kg/m³)

2595

Calcite

ASTMC97

2800

Dolomite

2690

Serpentine

2305

Travertine

Minimum compression (Mpa)

52

In all four groups

ASTMC170

Module of elasticity(Mpa)

7

In all four groups

ASTMC99

Min. grinding (hardness)

10

In all four groups

ASTMC241

Min. bending stress(Mpa)

7

In all four groups

ASTMC880

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