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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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<SEC-DOCUMENT>0000820478-07-000022.txt : 20070122
<SEC-HEADER>0000820478-07-000022.hdr.sgml : 20070122
<ACCEPTANCE-DATETIME>20070122155942
ACCESSION NUMBER:		0000820478-07-000022
CONFORMED SUBMISSION TYPE:	SC 13G
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20070122
DATE AS OF CHANGE:		20070122

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			TGC INDUSTRIES INC
		CENTRAL INDEX KEY:			0000799165
		STANDARD INDUSTRIAL CLASSIFICATION:	OIL AND GAS FIELD EXPLORATION SERVICES [1382]
		IRS NUMBER:				742095844
		STATE OF INCORPORATION:			TX
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-37717
		FILM NUMBER:		07543405

	BUSINESS ADDRESS:	
		STREET 1:		1304 SUMMIT AVE STE 2
		CITY:			PLANO
		STATE:			TX
		ZIP:			75074
		BUSINESS PHONE:		9728811099

	MAIL ADDRESS:	
		STREET 1:		1304 SUMMIT AVE
		STREET 2:		STE 2
		CITY:			PLANO
		STATE:			TX
		ZIP:			75074

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			STRS OHIO
		CENTRAL INDEX KEY:			0000820478
		IRS NUMBER:				311312155
		STATE OF INCORPORATION:			OH
		FISCAL YEAR END:			0630

	FILING VALUES:
		FORM TYPE:		SC 13G

	BUSINESS ADDRESS:	
		STREET 1:		275 EAST BROAD STREET
		CITY:			COLUMBUS
		STATE:			OH
		ZIP:			43215-3771
		BUSINESS PHONE:		6142274076

	MAIL ADDRESS:	
		STREET 1:		275 E BROAD ST
		CITY:			COLUMBUS
		STATE:			OH
		ZIP:			43215

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	STATE TEACHERS RETIREMENT SYSTEM OF OHIO
		DATE OF NAME CHANGE:	19970331
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13G
<SEQUENCE>1
<FILENAME>form13gtgedec06.htm
<DESCRIPTION>FORM 13G TGC DEC06
<TEXT>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML><HEAD><TITLE></TITLE>
<META content="MSHTML 6.00.2900.3020" name=GENERATOR></HEAD>
<BODY>
<P style="LINE-HEIGHT: 100%" align=center>&nbsp;</P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center><B>UNITED
STATES</B></P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center><B>SECURITIES AND
EXCHANGE COMMISSION</B></P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center>Washington, D.C.
20549</P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center>&nbsp;</P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center><B>SCHEDULE
13G</B></P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center><B>Under the
Securities Exchange Act of 1934</B></P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center>&nbsp;</P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center><B>T.G.C.
INDUSTRIES INC. (TGE)</B></P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center>(Name of
Issuer)</P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center>&nbsp;</P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center><B>COM </B></P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center>(Title of Class of
Securities)</P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center><B></B>&nbsp;</P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center><B>872417308
</B></P>
<P style="MARGIN-TOP: -15px; LINE-HEIGHT: 100%" align=center>(CUSIP Number)</P>
<P style="MARGIN-TOP: -20px"></P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>1) Names of Reporting Persons, IRS Identification Nos. of Above Persons:</P>
<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; OTR - Nominee Name for The State
Teachers Retirement Board of Ohio, 31-1312155</P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>2) Check the appropriate box if a member of a group*&nbsp;&nbsp;(a)
[_]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b) [_]</P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>3) SEC Use Only</P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>4) Citizenship or Place of Organization</P>
<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Columbus, Ohio</P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Number of Shares Beneficially Owned by Each Reporting Person With</P>
<P>5) Sole Voting Power&nbsp;&nbsp;&nbsp; 900000</P>
<P>6) Shared Voting Power&nbsp;&nbsp;&nbsp; 0</P>
<P>7) Sole Dispositive Power&nbsp;&nbsp;&nbsp; 900000</P>
<P>8) Shared Dispositive Power&nbsp;&nbsp;&nbsp; 0</P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>9) Aggregate Amount Beneficially Owned by Each Reporting
Person&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 900000</P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>10) Check if the Aggregate Amount in Row (9) Excludes Certain
Shares*&nbsp;&nbsp;[_]</P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>11) Percent of Class Represented by Amount in Row
(9)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 5.73</P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>12) Type of Reporting Person*&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; EP</P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>SCHEDULE 13G</P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Item 1</P>
<BLOCKQUOTE>
  <P>(a) Name of Issuer</P>
  <BLOCKQUOTE>
    <P style="MARGIN-TOP: -15px">This Statement on Schedule 13G relates to the
    shares of Instrument</P>
    <P style="MARGIN-TOP: -15px">T.G.C. INDUSTRIES INC. </P></BLOCKQUOTE>
  <P>(b) Address of Issuer's Principal Executive Offices:</P>
  <BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Item 2&nbsp;&nbsp;&nbsp;&nbsp;</P>
<BLOCKQUOTE>
  <P>(a) Name of Person Filing:</P>
  <BLOCKQUOTE>
    <P style="MARGIN-TOP: -15px">This Statement is filed by</P>
    <P style="MARGIN-TOP: -15px">OTR - Nominee Name for The State Teachers
    Retirement Board of Ohio</P></BLOCKQUOTE>
  <P>(b) Address of Principal Business Office:</P>
  <BLOCKQUOTE>
    <P style="MARGIN-TOP: -15px">The business address of OTR - Nominee Name for
    The State Teachers Retirement Board of Ohio is</P>
    <P style="MARGIN-TOP: -15px">275 East Broad Street</P>
    <P style="MARGIN-TOP: -15px">Columbus, Ohio 43215</P></BLOCKQUOTE>
  <P>(c) Citizenship:&nbsp;&nbsp;&nbsp;&nbsp; Not Applicable</P>
  <P>(d) Title of Class of Securities:</P>
  <BLOCKQUOTE>
    <P style="MARGIN-TOP: -15px">The securities are shares of COM
  .</P></BLOCKQUOTE>
  <P>(e) CUSIP No.:</P>
  <BLOCKQUOTE>
    <P style="MARGIN-TOP: -15px">The CUSIP Number for the investment is
    872417308 .</P></BLOCKQUOTE></BLOCKQUOTE>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Item 3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Type of Person
Filing:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</P>
<BLOCKQUOTE>
  <P>STRS is an employee benefit plan established for teachers of the public
  schools of Ohio to provide retirement allowances and other benefits under the
  terms of Chapter 3307 of the Ohio Revised Code.</P></BLOCKQUOTE>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Item 4&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;OWNERSHIP</P>
<BLOCKQUOTE>
  <P>(a) Amount Beneficially Owned:</P>
  <BLOCKQUOTE>
    <P style="MARGIN-TOP: -15px">STRS owns 900000 shares of T.G.C. INDUSTRIES
    INC. </P></BLOCKQUOTE>
  <P>(b) Percent of Class:</P>
  <BLOCKQUOTE>
    <P style="MARGIN-TOP: -15px">STRS believes that there are presently 15715000
    outstanding shares of T.G.C. INDUSTRIES INC. ; therefore, STRS' ownership of
    900000 shares of T.G.C. INDUSTRIES INC. stock is 5.73 percent of this
    class.</P></BLOCKQUOTE>
  <P>(c) Number of Shares As To Which Such Person Has Power:</P>
  <BLOCKQUOTE>
    <P>(i) Sole power to vote or to direct the vote&nbsp;&nbsp;&nbsp; 900000</P>
    <P>(ii) Shared power to vote or to direct the vote&nbsp;&nbsp;&nbsp; 0</P>
    <P>(iii) Sole power to dispose or to direct the disposition of
    &nbsp;&nbsp;&nbsp; 900000</P>
    <P>(iv) Shared power to dispose or to direct the disposition of 0 shares of
    T.G.C. INDUSTRIES INC. stock.</P></BLOCKQUOTE></BLOCKQUOTE>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Item 5&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; OWNERSHIP OF FIVE PERCENT OR
LESS OF A CLASS.
<BLOCKQUOTE>
  <P>If this statements is being filed to report the fact that as of the date
  hereof the reporting person has ceased to be the beneficial owner of more than
  five (5) percent of the class of securities, check the following [
].</P></BLOCKQUOTE>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Item 6&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; OWNERSHIP OF MORE THAN FIVE
PERCENT ON BEHALF OF ANOTHER PERSON</P>
<BLOCKQUOTE>
  <P>Not Applicable</P></BLOCKQUOTE>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Item 7&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; IDENTIFICATION AND
CLASSIFICATION OF SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY
THE PARENT HOLDING COMPANY.</P>
<BLOCKQUOTE>
  <P>Not Applicable</P></BLOCKQUOTE>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Item 8&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; IDENTIFICATION AND
CLASSIFICATION OF MEMBERS OF THE GROUP</P>
<BLOCKQUOTE>
  <P>Not Applicable</P></BLOCKQUOTE>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Item 9&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; NOTICE OF DISSOLUTION OF
GROUP</P>
<BLOCKQUOTE>
  <P>Not Applicable</P></BLOCKQUOTE>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>Item 10&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; CERTIFICATION</P>
<P>By signing below I certify that, to the best of my knowledge and belief, the
securities referred to above were acquired in the ordinary course of business
and were not acquired for the purpose of, and do not have the effect of,
changing or influencing the control of the issuer of such securities, and were
not acquired in connection with, or as a participant in, any transaction having
such purposes or effect. </P>
<P
style="MARGIN-TOP: -20px">&nbsp;________________________________________________________________________________</P>
<P>SIGNATURE</P>
<P>After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct. &nbsp;</P>
<P>DATED:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1/5/2007 </P>
<P>&nbsp;</P>
<P style="MARGIN-TOP: -20px">OTR - Nominee Name for The State Teachers
Retirement Board of Ohio</P>
<P style="MARGIN-TOP: -20px">275 East Broad Street</P>
<P style="MARGIN-TOP: -20px">Columbus, Ohio 43215</P>
<P style="MARGIN-TOP: -20px">STEPHEN A. MITCHELL</P>
<P style="MARGIN-TOP: -20px">/s/Stephen A. Mitchell</P>
<P>...........................................</P>
<P style="MARGIN-TOP: -20px">Stephen A. Mitchell</P>
<P style="MARGIN-TOP: -20px">Deputy Executive Director, Investments</P>
<P style="MARGIN-TOP: -20px">614-227-4003</P></BODY></HTML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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