CONFIDENTIAL TREATMENT REQUESTED

November 8, 1996


Dr. James R. McCormick
President & CEO
Hemlock Semiconductor Corporation
12334 Geddes Road
Hemlock, MI  48626

RE:     Agreement between Hemlock Semiconductor Corporation ("HSC") and
        MEMC Electronic Materials, Inc. ("MEMC") for the sale of Polycrystalline
        Silicon by HSC to MEMC dated December 27, 1994, as amended by Letter
        Agreement dated June 20, 1995 (the "Agreement")

Dear Dr. McCormick:

This  letter  confirms  our  understanding  to further  amend the  Agreement  as
follows:

1.   Paragraph 1.2 is amended in its entirety to read as follows:

     1.2  Base  Purchase  Quantity  for the  calendar  years  1996-2000  of this
Agreement is as follows:

     Year                    Base Purchase Quantity
     ----                    ----------------------

     1996 [CONFIDENTIAL MATERIAL HAS BEEN DELETED AND FILED SEPARATELY WITH SEC]
     1997 [CONFIDENTIAL MATERIAL HAS BEEN DELETED AND FILED SEPARATELY WITH SEC]
     1998 [CONFIDENTIAL MATERIAL HAS BEEN DELETED AND FILED SEPARATELY WITH SEC]
     1999 [CONFIDENTIAL MATERIAL HAS BEEN DELETED AND FILED SEPARATELY WITH SEC]
     2000 [CONFIDENTIAL MATERIAL HAS BEEN DELETED AND FILED SEPARATELY WITH SEC]

2.   Paragraph 1.8 is amended in its entirety to read as follows:

     1.8 Minimum  Purchase  Quantity  for the calendar  years  1996-2000 of this
Agreement is as follows:

     Year                    Minimum Purchase Quantity
     ----                    -------------------------

     1996 [CONFIDENTIAL MATERIAL HAS BEEN DELETED AND FILED SEPARATELY WITH SEC]
     1997 [CONFIDENTIAL MATERIAL HAS BEEN DELETED AND FILED SEPARATELY WITH SEC]
     1998 [CONFIDENTIAL MATERIAL HAS BEEN DELETED AND FILED SEPARATELY WITH SEC]
     1999 [CONFIDENTIAL MATERIAL HAS BEEN DELETED AND FILED SEPARATELY WITH SEC]
     2000 [CONFIDENTIAL MATERIAL HAS BEEN DELETED AND FILED SEPARATELY WITH SEC]

Other than as expressly  set forth  above,  the  Agreement  shall remain in full
force and effect.

If the foregoing is acceptable to you,  please indicate your agreement on behalf
of HSC by signing in the space  provided  below and returning one fully executed
copy to me.

                                   Sincerely yours,

                                   MEMC Electronic Materials, Inc.


                                   By:  /s/ Robert M. Sandfort
                                   Title:  President and Chief Operating Officer

AGREED AND ACCEPTED TO:

Hemlock Semiconductor Corporation


By: /s/ James R. McCormick
Title: President & CEO